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<div class="section" id="headers">
<h1>Headers<a class="headerlink" href="#headers" title="Permalink to this headline">¶</a></h1>
<div class="section" id="header">
<h2><a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-class docutils literal"><span class="pre">Header</span></tt></a><a class="headerlink" href="#header" title="Permalink to this headline">¶</a></h2>
<dl class="class">
<dt id="astropy.io.fits.Header">
<em class="property">class </em><tt class="descclassname">astropy.io.fits.</tt><tt class="descname">Header</tt><big>(</big><em>cards=</em><span class="optional">[</span><span class="optional">]</span>, <em>txtfile=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L35" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header" title="Permalink to this definition">¶</a></dt>
<dd><p>Bases: <tt class="xref py py-class docutils literal"><span class="pre">object</span></tt></p>
<p>FITS header class. This class exposes both a dict-like interface and a
list-like interface to FITS headers.</p>
<p>The header may be indexed by keyword and, like a dict, the associated value
will be returned. When the header contains cards with duplicate keywords,
only the value of the first card with the given keyword will be returned.
It is also possible to use a 2-tuple as the index in the form (keyword,
n)–this returns the n-th value with that keyword, in the case where there
are duplicate keywords.</p>
<p>For example:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="p">[</span><span class="s">'NAXIS'</span><span class="p">]</span>
<span class="go">0</span>
<span class="gp">>>> </span><span class="n">header</span><span class="p">[(</span><span class="s">'FOO'</span><span class="p">,</span> <span class="mi">1</span><span class="p">)]</span> <span class="c"># Return the value of the second FOO keyword</span>
<span class="go">'foo'</span>
</pre></div>
</div>
<p>The header may also be indexed by card number:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="p">[</span><span class="mi">0</span><span class="p">]</span> <span class="c"># Return the value of the first card in the header</span>
<span class="go">'T'</span>
</pre></div>
</div>
<p>Commentary keywords such as HISTORY and COMMENT are special cases: When
indexing the Header object with either ‘HISTORY’ or ‘COMMENT’ a list of all
the HISTORY/COMMENT values is returned:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="p">[</span><span class="s">'HISTORY'</span><span class="p">]</span>
<span class="go">This is the first history entry in this header.</span>
<span class="go">This is the second history entry in this header.</span>
<span class="gp">...</span>
</pre></div>
</div>
<p>See the Astropy documentation for more details on working with headers.</p>
<dl class="method">
<dt id="astropy.io.fits.Header.add_blank">
<tt class="descname">add_blank</tt><big>(</big><em>value=''</em>, <em>before=None</em>, <em>after=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1499" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.add_blank" title="Permalink to this definition">¶</a></dt>
<dd><p>Add a blank card.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>value</strong> : str, optional</p>
<blockquote>
<div><p>text to be added.</p>
</div></blockquote>
<p><strong>before</strong> : str or int, optional</p>
<blockquote>
<div><p>same as in <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-obj docutils literal"><span class="pre">Header.update</span></tt></a></p>
</div></blockquote>
<p><strong>after</strong> : str or int, optional</p>
<blockquote class="last">
<div><p>same as in <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-obj docutils literal"><span class="pre">Header.update</span></tt></a></p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.add_comment">
<tt class="descname">add_comment</tt><big>(</big><em>value</em>, <em>before=None</em>, <em>after=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1481" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.add_comment" title="Permalink to this definition">¶</a></dt>
<dd><p>Add a <tt class="docutils literal"><span class="pre">COMMENT</span></tt> card.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>value</strong> : str</p>
<blockquote>
<div><p>text to be added.</p>
</div></blockquote>
<p><strong>before</strong> : str or int, optional</p>
<blockquote>
<div><p>same as in <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-obj docutils literal"><span class="pre">Header.update</span></tt></a></p>
</div></blockquote>
<p><strong>after</strong> : str or int, optional</p>
<blockquote class="last">
<div><p>same as in <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-obj docutils literal"><span class="pre">Header.update</span></tt></a></p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.add_history">
<tt class="descname">add_history</tt><big>(</big><em>value</em>, <em>before=None</em>, <em>after=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1463" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.add_history" title="Permalink to this definition">¶</a></dt>
<dd><p>Add a <tt class="docutils literal"><span class="pre">HISTORY</span></tt> card.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>value</strong> : str</p>
<blockquote>
<div><p>history text to be added.</p>
</div></blockquote>
<p><strong>before</strong> : str or int, optional</p>
<blockquote>
<div><p>same as in <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-obj docutils literal"><span class="pre">Header.update</span></tt></a></p>
</div></blockquote>
<p><strong>after</strong> : str or int, optional</p>
<blockquote class="last">
<div><p>same as in <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-obj docutils literal"><span class="pre">Header.update</span></tt></a></p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.append">
<tt class="descname">append</tt><big>(</big><em>card=None</em>, <em>useblanks=True</em>, <em>bottom=False</em>, <em>end=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1099" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.append" title="Permalink to this definition">¶</a></dt>
<dd><p>Appends a new keyword+value card to the end of the Header, similar
to list.append().</p>
<p>By default if the last cards in the Header have commentary keywords,
this will append the new keyword before the commentary (unless the new
keyword is also commentary).</p>
<p>Also differs from list.append() in that it can be called with no
arguments: In this case a blank card is appended to the end of the
Header. In the case all the keyword arguments are ignored.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>card</strong> : str, tuple</p>
<blockquote>
<div><p>A keyword or a (keyword, value, [comment]) tuple representing a
single header card; the comment is optional in which case a
2-tuple may be used</p>
</div></blockquote>
<p><strong>useblanks</strong> : bool (optional)</p>
<blockquote>
<div><p>If there are blank cards at the end of the Header, replace the
first blank card so that the total number of cards in the Header
does not increase. Otherwise preserve the number of blank cards.</p>
</div></blockquote>
<p><strong>bottom</strong> : bool (optional)</p>
<blockquote>
<div><p>If True, instead of appending after the last non-commentary card,
append after the last non-blank card.</p>
</div></blockquote>
<p><strong>end</strong> : bool (optional):</p>
<blockquote class="last">
<div><p>If True, ignore the useblanks and bottom options, and append at the
very end of the Header.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="attribute">
<dt id="astropy.io.fits.Header.ascard">
<tt class="descname">ascard</tt><a class="headerlink" href="#astropy.io.fits.Header.ascard" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.1: </span>Use the <a class="reference internal" href="#astropy.io.fits.Header.cards" title="astropy.io.fits.Header.cards"><tt class="xref py py-obj docutils literal"><span class="pre">cards</span></tt></a> attribute instead.</p>
<p>Returns a CardList object wrapping this Header; provided for
backwards compatibility for the old API (where Headers had an
underlying CardList).</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.ascardlist">
<tt class="descname">ascardlist</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.ascardlist" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.0: </span>Use the <a class="reference internal" href="#astropy.io.fits.Header.ascard" title="astropy.io.fits.Header.ascard"><tt class="xref py py-obj docutils literal"><span class="pre">ascard</span></tt></a> attribute instead.</p>
<p>Returns a <a class="reference internal" href="cards.html#astropy.io.fits.CardList" title="astropy.io.fits.CardList"><tt class="xref py py-obj docutils literal"><span class="pre">CardList</span></tt></a> object.</p>
</dd></dl>
<dl class="attribute">
<dt id="astropy.io.fits.Header.cards">
<tt class="descname">cards</tt><a class="headerlink" href="#astropy.io.fits.Header.cards" title="Permalink to this definition">¶</a></dt>
<dd><p>The underlying physical cards that make up this Header; it can be
looked at, but it should not be modified directly.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.clear">
<tt class="descname">clear</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L649" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.clear" title="Permalink to this definition">¶</a></dt>
<dd><p>Remove all cards from the header.</p>
</dd></dl>
<dl class="attribute">
<dt id="astropy.io.fits.Header.comments">
<tt class="descname">comments</tt><a class="headerlink" href="#astropy.io.fits.Header.comments" title="Permalink to this definition">¶</a></dt>
<dd><p>View the comments associated with each keyword, if any.</p>
<p>For example, to see the comment on the NAXIS keyword:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">comments</span><span class="p">[</span><span class="s">'NAXIS'</span><span class="p">]</span>
<span class="go">number of data axes</span>
</pre></div>
</div>
<p>Comments can also be updated through this interface:</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">comments</span><span class="p">[</span><span class="s">'NAXIS'</span><span class="p">]</span> <span class="o">=</span> <span class="s">'Number of data axes'</span>
</pre></div>
</div>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.copy">
<tt class="descname">copy</tt><big>(</big><em>strip=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L657" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.copy" title="Permalink to this definition">¶</a></dt>
<dd><p>Make a copy of the <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-class docutils literal"><span class="pre">Header</span></tt></a>.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>strip</strong> : bool (optional)</p>
<blockquote>
<div><p>If True, strip any headers that are specific to one of the standard
HDU types, so that this header can be used in a different HDU.</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>header</strong> :</p>
<blockquote class="last">
<div><p>A new <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-class docutils literal"><span class="pre">Header</span></tt></a> instance.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.count">
<tt class="descname">count</tt><big>(</big><em>keyword</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1283" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.count" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns the count of the given keyword in the header, similar to
list.count() if the Header object is treated as a list of keywords.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>keyword</strong> : str</p>
<blockquote class="last">
<div><p>The keyword to count instances of in the header</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.extend">
<tt class="descname">extend</tt><big>(</big><em>cards</em>, <em>strip=True</em>, <em>unique=False</em>, <em>update=False</em>, <em>update_first=False</em>, <em>useblanks=True</em>, <em>bottom=False</em>, <em>end=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1182" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.extend" title="Permalink to this definition">¶</a></dt>
<dd><p>Appends multiple keyword+value cards to the end of the header, similar
to list.extend().</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>cards</strong> : iterable</p>
<blockquote>
<div><p>An iterable of (keyword, value, [comment]) tuples; see
Header.append()</p>
</div></blockquote>
<p><strong>strip</strong> : bool (optional)</p>
<blockquote>
<div><p>Remove any keywords that have meaning only to specific types of
HDUs, so that only more general keywords are added from extension
Header or Card list (default: True).</p>
</div></blockquote>
<p><strong>unique</strong> : bool (optional)</p>
<blockquote>
<div><p>If <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, ensures that no duplicate keywords are appended;
keywords already in this header are simply discarded. The
exception is commentary keywords (COMMENT, HISTORY, etc.): they are
only treated as duplicates if their values match.</p>
</div></blockquote>
<p><strong>update</strong> : bool (optional)</p>
<blockquote>
<div><p>If <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, update the current header with the values and comments
from duplicate keywords in the input header. This supercedes the
<tt class="xref py py-obj docutils literal"><span class="pre">unique</span></tt> argument. Commentary keywords are treated the same as if
<tt class="xref py py-obj docutils literal"><span class="pre">unique=True</span></tt>.</p>
</div></blockquote>
<p><strong>update_first</strong> : bool (optional)</p>
<blockquote>
<div><p>If the first keyword in the header is ‘SIMPLE’, and the first
keyword in the input header is ‘XTENSION’, the ‘SIMPLE’ keyword is
replaced by the ‘XTENSION’ keyword. Likewise if the first keyword
in the header is ‘XTENSION’ and the first keyword in the input
header is ‘SIMPLE’, the ‘XTENSION’ keyword is replaced by the
‘SIMPLE’ keyword. This behavior is otherwise dumb as to whether or
not the resulting header is a valid primary or extension header.
This is mostly provided to support backwards compatibility with the
old <a class="reference internal" href="#astropy.io.fits.Header.fromTxtFile" title="astropy.io.fits.Header.fromTxtFile"><tt class="xref py py-meth docutils literal"><span class="pre">Header.fromTxtFile()</span></tt></a> method, and only applies if
<tt class="xref py py-obj docutils literal"><span class="pre">update=True</span></tt>.</p>
</div></blockquote>
<p><strong>useblanks, bottom, end</strong> : bool (optional)</p>
<blockquote class="last">
<div><p>These arguments are passed to <a class="reference internal" href="#astropy.io.fits.Header.append" title="astropy.io.fits.Header.append"><tt class="xref py py-meth docutils literal"><span class="pre">Header.append()</span></tt></a> while appending
new cards to the header.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.fromTxtFile">
<tt class="descname">fromTxtFile</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.fromTxtFile" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.1: </span>This is equivalent to <tt class="docutils literal"><span class="pre">self.extend(Header.fromtextfile(fileobj),</span> <span class="pre">update=True,</span> <span class="pre">update_first=True)</span></tt>. Note that there there is no direct equivalent to the <tt class="docutils literal"><span class="pre">replace=True</span></tt> option since <a class="reference internal" href="#astropy.io.fits.Header.fromtextfile" title="astropy.io.fits.Header.fromtextfile"><tt class="xref py py-meth docutils literal"><span class="pre">Header.fromtextfile()</span></tt></a> returns a new <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-class docutils literal"><span class="pre">Header</span></tt></a> instance.</p>
<p>Input the header parameters from an ASCII file.</p>
<p>The input header cards will be used to update the current
header. Therefore, when an input card key matches a card key
that already exists in the header, that card will be updated
in place. Any input cards that do not already exist in the
header will be added. Cards will not be deleted from the
header.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>fileobj</strong> : file path, file object or file-like object</p>
<blockquote>
<div><p>Input header parameters file.</p>
</div></blockquote>
<p><strong>replace</strong> : bool, optional</p>
<blockquote class="last">
<div><p>When <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, indicates that the entire header should be
replaced with the contents of the ASCII file instead of
just updating the current header.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="classmethod">
<dt id="astropy.io.fits.Header.fromfile">
<em class="property">classmethod </em><tt class="descname">fromfile</tt><big>(</big><em>fileobj</em>, <em>sep=''</em>, <em>endcard=True</em>, <em>padding=True</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L386" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.fromfile" title="Permalink to this definition">¶</a></dt>
<dd><p>Similar to <a class="reference internal" href="#astropy.io.fits.Header.fromstring" title="astropy.io.fits.Header.fromstring"><tt class="xref py py-meth docutils literal"><span class="pre">Header.fromstring()</span></tt></a>, but reads the header string from
a given file-like object or filename.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>fileobj</strong> : str, file-like</p>
<blockquote>
<div><p>A filename or an open file-like object from which a FITS header is
to be read. For open file handles the file pointer must be at the
beginning of the header.</p>
</div></blockquote>
<p><strong>sep</strong> : str (optional)</p>
<blockquote>
<div><p>The string separating cards from each other, such as a newline. By
default there is no card separator (as is the case in a raw FITS
file).</p>
</div></blockquote>
<p><strong>endcard</strong> : bool (optional)</p>
<blockquote>
<div><p>If True (the default) the header must end with an END card in order
to be considered valid. If an END card is not found an <tt class="xref py py-obj docutils literal"><span class="pre">IOError</span></tt>
is raised.</p>
</div></blockquote>
<p><strong>padding</strong> : bool (optional)</p>
<blockquote>
<div><p>If True (the default) the header will be required to be padded out
to a multiple of 2880, the FITS header block size. Otherwise any
padding, or lack thereof, is ignored.</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>header</strong> :</p>
<blockquote class="last">
<div><p>A new <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-obj docutils literal"><span class="pre">Header</span></tt></a> instance.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="classmethod">
<dt id="astropy.io.fits.Header.fromkeys">
<em class="property">classmethod </em><tt class="descname">fromkeys</tt><big>(</big><em>iterable</em>, <em>value=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L678" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.fromkeys" title="Permalink to this definition">¶</a></dt>
<dd><p>Similar to <tt class="xref py py-meth docutils literal"><span class="pre">dict.fromkeys()</span></tt>–creates a new <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-obj docutils literal"><span class="pre">Header</span></tt></a> from an
iterable of keywords and an optional default value.</p>
<p>This method is not likely to be particularly useful for creating real
world FITS headers, but it is useful for testing.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>iterable</strong> :</p>
<blockquote>
<div><p>Any iterable that returns strings representing FITS keywords.</p>
</div></blockquote>
<p><strong>value</strong> : (optional)</p>
<blockquote>
<div><p>A default value to assign to each keyword; must be a valid type for
FITS keywords.</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>header</strong> :</p>
<blockquote class="last">
<div><p>A new <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-obj docutils literal"><span class="pre">Header</span></tt></a> instance.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="classmethod">
<dt id="astropy.io.fits.Header.fromstring">
<em class="property">classmethod </em><tt class="descname">fromstring</tt><big>(</big><em>data</em>, <em>sep=''</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L314" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.fromstring" title="Permalink to this definition">¶</a></dt>
<dd><p>Creates an HDU header from a byte string containing the entire header
data.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>data</strong> : str</p>
<blockquote>
<div><p>String containing the entire header.</p>
</div></blockquote>
<p><strong>sep</strong> : str (optional)</p>
<blockquote>
<div><p>The string separating cards from each other, such as a newline. By
default there is no card separator (as is the case in a raw FITS
file).</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>header</strong> :</p>
<blockquote class="last">
<div><p>A new <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-obj docutils literal"><span class="pre">Header</span></tt></a> instance.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="classmethod">
<dt id="astropy.io.fits.Header.fromtextfile">
<em class="property">classmethod </em><tt class="descname">fromtextfile</tt><big>(</big><em>fileobj</em>, <em>endcard=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L631" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.fromtextfile" title="Permalink to this definition">¶</a></dt>
<dd><p>Equivalent to <tt class="docutils literal"><span class="pre">Header.fromfile(fileobj,</span> <span class="pre">sep='\n',</span> <span class="pre">endcard=False,</span>
<span class="pre">padding=False)</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.get">
<tt class="descname">get</tt><big>(</big><em>key</em>, <em>default=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L709" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.get" title="Permalink to this definition">¶</a></dt>
<dd><p>Similar to <tt class="xref py py-meth docutils literal"><span class="pre">dict.get()</span></tt>–returns the value associated with keyword
in the header, or a default value if the keyword is not found.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>key</strong> : str</p>
<blockquote>
<div><p>A keyword that may or may not be in the header.</p>
</div></blockquote>
<p><strong>default</strong> : (optional)</p>
<blockquote>
<div><p>A default value to return if the keyword is not found in the
header.</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>value</strong> :</p>
<blockquote class="last">
<div><p>The value associated with the given keyword, or the default value
if the keyword is not in the header.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.get_comment">
<tt class="descname">get_comment</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.get_comment" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.1: </span>Use <tt class="docutils literal"><span class="pre">header['COMMENT']</span></tt> instead.</p>
<p>Get all comment cards as a list of string texts.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.get_history">
<tt class="descname">get_history</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.get_history" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.1: </span>Use <tt class="docutils literal"><span class="pre">header['HISTORY']</span></tt> instead.</p>
<p>Get all history cards as a list of string texts.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.has_key">
<tt class="descname">has_key</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.has_key" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.0: </span>Use <tt class="docutils literal"><span class="pre">key</span> <span class="pre">in</span> <span class="pre">header</span></tt> syntax instead.</p>
<p>Like <tt class="xref py py-meth docutils literal"><span class="pre">dict.has_key()</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.index">
<tt class="descname">index</tt><big>(</big><em>keyword</em>, <em>start=None</em>, <em>stop=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1304" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.index" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns the index if the first instance of the given keyword in the
header, similar to list.index() if the Header object is treated as a
list of keywords.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>keyword</strong> : str</p>
<blockquote>
<div><p>The keyword to look up in the list of all keywords in the header</p>
</div></blockquote>
<p><strong>start</strong> : int (optional)</p>
<blockquote>
<div><p>The lower bound for the index</p>
</div></blockquote>
<p><strong>stop</strong> : int (optional)</p>
<blockquote class="last">
<div><p>The upper bound for the index</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.insert">
<tt class="descname">insert</tt><big>(</big><em>idx</em>, <em>card</em>, <em>useblanks=True</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1342" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.insert" title="Permalink to this definition">¶</a></dt>
<dd><p>Inserts a new keyword+value card into the Header at a given location,
similar to list.insert().</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>idx</strong> : int</p>
<blockquote>
<div><p>The index into the the list of header keywords before which the
new keyword should be inserted</p>
</div></blockquote>
<p><strong>card</strong> : str, tuple</p>
<blockquote>
<div><p>A keyword or a (keyword, value, [comment]) tuple; see
Header.append()</p>
</div></blockquote>
<p><strong>useblanks</strong> : bool (optional)</p>
<blockquote class="last">
<div><p>If there are blank cards at the end of the Header, replace the
first blank card so that the total number of cards in the Header
does not increase. Otherwise preserve the number of blank cards.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.items">
<tt class="descname">items</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L825" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.items" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <tt class="xref py py-meth docutils literal"><span class="pre">dict.items()</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.iteritems">
<tt class="descname">iteritems</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L830" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.iteritems" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <tt class="xref py py-meth docutils literal"><span class="pre">dict.iteritems()</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.iterkeys">
<tt class="descname">iterkeys</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L836" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.iterkeys" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <tt class="xref py py-meth docutils literal"><span class="pre">dict.iterkeys()</span></tt>–iterating directly over the <a class="reference internal" href="#astropy.io.fits.Header" title="astropy.io.fits.Header"><tt class="xref py py-obj docutils literal"><span class="pre">Header</span></tt></a>
instance has the same behavior.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.itervalues">
<tt class="descname">itervalues</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L844" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.itervalues" title="Permalink to this definition">¶</a></dt>
<dd><p>Like <tt class="xref py py-meth docutils literal"><span class="pre">dict.itervalues()</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.keys">
<tt class="descname">keys</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L850" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.keys" title="Permalink to this definition">¶</a></dt>
<dd><p>Return a list of keywords in the header in the order they
appear–like:meth:<tt class="xref py py-obj docutils literal"><span class="pre">dict.keys</span></tt> but ordered.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.pop">
<tt class="descname">pop</tt><big>(</big><em>*args</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L858" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.pop" title="Permalink to this definition">¶</a></dt>
<dd><p>Works like <tt class="xref py py-meth docutils literal"><span class="pre">list.pop()</span></tt> if no arguments or an index argument are
supplied; otherwise works like <tt class="xref py py-meth docutils literal"><span class="pre">dict.pop()</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.popitem">
<tt class="descname">popitem</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L883" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.popitem" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.remove">
<tt class="descname">remove</tt><big>(</big><em>keyword</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1409" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.remove" title="Permalink to this definition">¶</a></dt>
<dd><p>Removes the first instance of the given keyword from the header
similar to list.remove() if the Header object is treated as a list of
keywords.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>value</strong> : str</p>
<blockquote class="last">
<div><p>The keyword of which to remove the first instance in the header</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.rename_key">
<tt class="descname">rename_key</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.rename_key" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.1: </span>Use <a class="reference internal" href="#astropy.io.fits.Header.rename_keyword" title="astropy.io.fits.Header.rename_keyword"><tt class="xref py py-meth docutils literal"><span class="pre">Header.rename_keyword()</span></tt></a> instead.</p>
<p></p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.rename_keyword">
<tt class="descname">rename_keyword</tt><big>(</big><em>oldkeyword</em>, <em>newkeyword</em>, <em>force=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1424" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.rename_keyword" title="Permalink to this definition">¶</a></dt>
<dd><p>Rename a card’s keyword in the header.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>oldkeyword</strong> : str or int</p>
<blockquote>
<div><p>Old keyword or card index</p>
</div></blockquote>
<p><strong>newkeyword</strong> : str</p>
<blockquote>
<div><p>New keyword</p>
</div></blockquote>
<p><strong>force</strong> : bool (optional)</p>
<blockquote class="last">
<div><p>When <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, if the new keyword already exists in the header, force
the creation of a duplicate keyword. Otherwise a <tt class="xref py py-obj docutils literal"><span class="pre">ValueError</span></tt> is
raised.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.set">
<tt class="descname">set</tt><big>(</big><em>keyword</em>, <em>value=None</em>, <em>comment=None</em>, <em>before=None</em>, <em>after=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L735" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.set" title="Permalink to this definition">¶</a></dt>
<dd><p>Set the value and/or comment and/or position of a specified keyword.</p>
<p>If the keyword does not already exist in the header, a new keyword is
created in the specified position, or appended to the end of the header
if no position is specified.</p>
<p>This method is similar to <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-meth docutils literal"><span class="pre">Header.update()</span></tt></a> prior to PyFITS 3.1.</p>
<div class="admonition note">
<p class="first admonition-title">Note</p>
<p>It should be noted that <tt class="docutils literal"><span class="pre">header.set(keyword,</span> <span class="pre">value)</span></tt> and
<tt class="docutils literal"><span class="pre">header.set(keyword,</span> <span class="pre">value,</span> <span class="pre">comment)</span></tt> are equivalent to
<tt class="docutils literal"><span class="pre">header[keyword]</span> <span class="pre">=</span> <span class="pre">value</span></tt> and
<tt class="docutils literal"><span class="pre">header[keyword]</span> <span class="pre">=</span> <span class="pre">(value,</span> <span class="pre">comment)</span></tt> respectfully.</p>
<p>New keywords can also be inserted relative to existing keywords
using, for example
<tt class="docutils literal"><span class="pre">header.insert('NAXIS1',</span> <span class="pre">('NAXIS',</span> <span class="pre">2,</span> <span class="pre">'Number</span> <span class="pre">of</span> <span class="pre">axes'))</span></tt> to
insert before an existing keyword, or
<tt class="docutils literal"><span class="pre">header.insert('NAXIS',</span> <span class="pre">('NAXIS1',</span> <span class="pre">4096),</span> <span class="pre">after=True)</span></tt> to insert
after an existing keyword.</p>
<p class="last">The the only advantage of using <a class="reference internal" href="#astropy.io.fits.Header.set" title="astropy.io.fits.Header.set"><tt class="xref py py-meth docutils literal"><span class="pre">Header.set()</span></tt></a> is that it
easily replaces the old usage of <a class="reference internal" href="#astropy.io.fits.Header.update" title="astropy.io.fits.Header.update"><tt class="xref py py-meth docutils literal"><span class="pre">Header.update()</span></tt></a> both
conceptually and in terms of function signature.</p>
</div>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>keyword</strong> : str</p>
<blockquote>
<div><p>A header keyword</p>
</div></blockquote>
<p><strong>value</strong> : str (optional)</p>
<blockquote>
<div><p>The value to set for the given keyword; if None the existing value
is kept, but ‘’ may be used to set a blank value</p>
</div></blockquote>
<p><strong>comment</strong> : str (optional)</p>
<blockquote>
<div><p>The comment to set for the given keyword; if None the existing
comment is kept, but ‘’ may be used to set a blank comment</p>
</div></blockquote>
<p><strong>before</strong> : str, int (optional)</p>
<blockquote>
<div><p>Name of the keyword, or index of the <a class="reference internal" href="cards.html#astropy.io.fits.Card" title="astropy.io.fits.Card"><tt class="xref py py-obj docutils literal"><span class="pre">Card</span></tt></a> before which
this card should be located in the header. The argument <tt class="xref py py-obj docutils literal"><span class="pre">before</span></tt>
takes precedence over <tt class="xref py py-obj docutils literal"><span class="pre">after</span></tt> if both specified.</p>
</div></blockquote>
<p><strong>after</strong> : str, int (optional)</p>
<blockquote class="last">
<div><p>Name of the keyword, or index of the <a class="reference internal" href="cards.html#astropy.io.fits.Card" title="astropy.io.fits.Card"><tt class="xref py py-obj docutils literal"><span class="pre">Card</span></tt></a> after which this card
should be located in the header.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.setdefault">
<tt class="descname">setdefault</tt><big>(</big><em>key</em>, <em>default=None</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L891" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.setdefault" title="Permalink to this definition">¶</a></dt>
<dd></dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.toTxtFile">
<tt class="descname">toTxtFile</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L380" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.toTxtFile" title="Permalink to this definition">¶</a></dt>
<dd><p class="deprecated">
<span class="versionmodified">Deprecated since version 3.1: </span>Use <a class="reference internal" href="#astropy.io.fits.Header.totextfile" title="astropy.io.fits.Header.totextfile"><tt class="xref py py-meth docutils literal"><span class="pre">Header.totextfile()</span></tt></a> instead.</p>
<p>Output the header parameters to a file in ASCII format.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>fileobj</strong> : file path, file object or file-like object</p>
<blockquote>
<div><p>Output header parameters file.</p>
</div></blockquote>
<p><strong>clobber</strong> : bool</p>
<blockquote class="last">
<div><p>When <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, overwrite the output file if it exists.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.tofile">
<tt class="descname">tofile</tt><big>(</big><em>fileobj</em>, <em>sep=''</em>, <em>endcard=True</em>, <em>padding=True</em>, <em>clobber=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L549" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.tofile" title="Permalink to this definition">¶</a></dt>
<dd><p>Writes the header to file or file-like object.</p>
<p>By default this writes the header exactly as it would be written to a
FITS file, with the END card included and padding to the next multiple
of 2880 bytes. However, aspects of this may be controlled.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>fileobj</strong> : str, file (optional)</p>
<blockquote>
<div><p>Either the pathname of a file, or an open file handle or file-like
object</p>
</div></blockquote>
<p><strong>sep</strong> : str (optional)</p>
<blockquote>
<div><p>The character or string with which to separate cards. By default
there is no separator, but one could use <tt class="xref py py-obj docutils literal"><span class="pre">'\n'</span></tt>, for example, to
separate each card with a new line</p>
</div></blockquote>
<p><strong>endcard</strong> : bool (optional)</p>
<blockquote>
<div><p>If <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> (default) adds the END card to the end of the header
string</p>
</div></blockquote>
<p><strong>padding</strong> : bool (optional)</p>
<blockquote>
<div><p>If <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt> (default) pads the string with spaces out to the next
multiple of 2880 characters</p>
</div></blockquote>
<p><strong>clobber</strong> : bool (optional)</p>
<blockquote class="last">
<div><p>If <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, overwrites the output file if it already exists</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.tostring">
<tt class="descname">tostring</tt><big>(</big><em>sep=''</em>, <em>endcard=True</em>, <em>padding=True</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L504" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.tostring" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns a string representation of the header.</p>
<p>By default this uses no separator between cards, adds the END card, and
pads the string with spaces to the next multiple of 2880 bytes. That
is, it returns the header exactly as it would appear in a FITS file.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>sep</strong> : str (optional)</p>
<blockquote>
<div><p>The character or string with which to separate cards. By default
there is no separator, but one could use <tt class="xref py py-obj docutils literal"><span class="pre">'\n'</span></tt>, for example, to
separate each card with a new line</p>
</div></blockquote>
<p><strong>endcard</strong> : bool (optional)</p>
<blockquote>
<div><p>If True (default) adds the END card to the end of the header
string</p>
</div></blockquote>
<p><strong>padding</strong> : bool (optional)</p>
<blockquote>
<div><p>If True (default) pads the string with spaces out to the next
multiple of 2880 characters</p>
</div></blockquote>
</td>
</tr>
<tr class="field-even field"><th class="field-name">Returns :</th><td class="field-body"><p class="first"><strong>s</strong> : string</p>
<blockquote class="last">
<div><p>A string representing a FITS header.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.totextfile">
<tt class="descname">totextfile</tt><big>(</big><em>fileobj</em>, <em>endcard=False</em>, <em>clobber=False</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L640" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.totextfile" title="Permalink to this definition">¶</a></dt>
<dd><p>Equivalent to <tt class="docutils literal"><span class="pre">Header.tofile(fileobj,</span> <span class="pre">sep='\n',</span> <span class="pre">endcard=False,</span>
<span class="pre">padding=False,</span> <span class="pre">clobber=clobber)</span></tt>.</p>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.update">
<tt class="descname">update</tt><big>(</big><em>*args</em>, <em>**kwargs</em><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L898" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.update" title="Permalink to this definition">¶</a></dt>
<dd><p>Update the Header with new keyword values, updating the values of
existing keywords and appending new keywords otherwise; similar to
dict.update().</p>
<p>update() accepts either a dict-like object or an iterable. In the
former case the keys must be header keywords and the values may be
either scalar values or (value, comment) tuples. In the case of an
iterable the items must be (keyword, value) tuples or
(keyword, value, comment) tuples.</p>
<p>Arbitrary arguments are also accepted, in which case the update() is
called again with the kwargs dict as its only argument. That is,</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">NAXIS1</span><span class="o">=</span><span class="mi">100</span><span class="p">,</span> <span class="n">NAXIS2</span><span class="o">=</span><span class="mi">100</span><span class="p">)</span>
</pre></div>
</div>
<p>is equivalent to</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">update</span><span class="p">({</span><span class="s">'NAXIS1'</span><span class="p">:</span> <span class="mi">100</span><span class="p">,</span> <span class="s">'NAXIS2'</span><span class="p">:</span> <span class="mi">100</span><span class="p">})</span>
</pre></div>
</div>
<div class="admonition warning">
<p class="first admonition-title">Warning</p>
<p>As this method works similarly to dict.update() it is very
different from the Header.update() method in PyFITS versions prior
to 3.1.0. However, support for the old API is also maintained for
backwards compatibility. If update() is called with at least two
positional arguments then it can be assumed that the old API is
being used. Use of the old API should be considered
<strong>deprecated</strong>. Most uses of the old API can be replaced as
follows:</p>
<ul>
<li><p class="first">Replace</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">keyword</span><span class="p">,</span> <span class="n">value</span><span class="p">)</span>
</pre></div>
</div>
<p>with</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="p">[</span><span class="n">keyword</span><span class="p">]</span> <span class="o">=</span> <span class="n">value</span>
</pre></div>
</div>
</li>
<li><p class="first">Replace</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">keyword</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">comment</span><span class="o">=</span><span class="n">comment</span><span class="p">)</span>
</pre></div>
</div>
<p>with</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="p">[</span><span class="n">keyword</span><span class="p">]</span> <span class="o">=</span> <span class="p">(</span><span class="n">value</span><span class="p">,</span> <span class="n">comment</span><span class="p">)</span>
</pre></div>
</div>
</li>
<li><p class="first">Replace</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">keyword</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">before</span><span class="o">=</span><span class="n">before_keyword</span><span class="p">)</span>
</pre></div>
</div>
<p>with</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">insert</span><span class="p">(</span><span class="n">before_keyword</span><span class="p">,</span> <span class="p">(</span><span class="n">keyword</span><span class="p">,</span> <span class="n">value</span><span class="p">))</span>
</pre></div>
</div>
</li>
<li><p class="first">Replace</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">update</span><span class="p">(</span><span class="n">keyword</span><span class="p">,</span> <span class="n">value</span><span class="p">,</span> <span class="n">after</span><span class="o">=</span><span class="n">after_keyword</span><span class="p">)</span>
</pre></div>
</div>
<p>with</p>
<div class="highlight-python"><div class="highlight"><pre><span class="gp">>>> </span><span class="n">header</span><span class="o">.</span><span class="n">insert</span><span class="p">(</span><span class="n">after_keyword</span><span class="p">,</span> <span class="p">(</span><span class="n">keyword</span><span class="p">,</span> <span class="n">value</span><span class="p">),</span>
<span class="gp">... </span> <span class="n">after</span><span class="o">=</span><span class="bp">True</span><span class="p">)</span>
</pre></div>
</div>
</li>
</ul>
<p>See also <a class="reference internal" href="#astropy.io.fits.Header.set" title="astropy.io.fits.Header.set"><tt class="xref py py-meth docutils literal"><span class="pre">Header.set()</span></tt></a> which is a new method that provides an
interface similar to the old Header.update() and may help make
transition a little easier.</p>
<p class="last">For reference, the old documentation for the old Header.update()
is provided below:</p>
</div>
<p>Update one header card.</p>
<p>If the keyword already exists, it’s value and/or comment will
be updated. If it does not exist, a new card will be created
and it will be placed before or after the specified location.
If no <tt class="xref py py-obj docutils literal"><span class="pre">before</span></tt> or <tt class="xref py py-obj docutils literal"><span class="pre">after</span></tt> is specified, it will be appended at
the end.</p>
<table class="docutils field-list" frame="void" rules="none">
<col class="field-name" />
<col class="field-body" />
<tbody valign="top">
<tr class="field-odd field"><th class="field-name">Parameters :</th><td class="field-body"><p class="first"><strong>key</strong> : str</p>
<blockquote>
<div><p>keyword</p>
</div></blockquote>
<p><strong>value</strong> : str</p>
<blockquote>
<div><p>value to be used for updating</p>
</div></blockquote>
<p><strong>comment</strong> : str (optional)</p>
<blockquote>
<div><p>to be used for updating, default=None.</p>
</div></blockquote>
<p><strong>before</strong> : str, int (optional)</p>
<blockquote>
<div><p>name of the keyword, or index of the <a class="reference internal" href="cards.html#astropy.io.fits.Card" title="astropy.io.fits.Card"><tt class="xref py py-obj docutils literal"><span class="pre">Card</span></tt></a> before which
the new card will be placed. The argument <tt class="xref py py-obj docutils literal"><span class="pre">before</span></tt> takes
precedence over <tt class="xref py py-obj docutils literal"><span class="pre">after</span></tt> if both specified.</p>
</div></blockquote>
<p><strong>after</strong> : str, int (optional)</p>
<blockquote>
<div><p>name of the keyword, or index of the <a class="reference internal" href="cards.html#astropy.io.fits.Card" title="astropy.io.fits.Card"><tt class="xref py py-obj docutils literal"><span class="pre">Card</span></tt></a> after which
the new card will be placed.</p>
</div></blockquote>
<p><strong>savecomment</strong> : bool (optional)</p>
<blockquote class="last">
<div><p>When <tt class="xref py py-obj docutils literal"><span class="pre">True</span></tt>, preserve the current comment for an existing
keyword. The argument <tt class="xref py py-obj docutils literal"><span class="pre">savecomment</span></tt> takes precedence over
<tt class="xref py py-obj docutils literal"><span class="pre">comment</span></tt> if both specified. If <tt class="xref py py-obj docutils literal"><span class="pre">comment</span></tt> is not
specified then the current comment will automatically be
preserved.</p>
</div></blockquote>
</td>
</tr>
</tbody>
</table>
</dd></dl>
<dl class="method">
<dt id="astropy.io.fits.Header.values">
<tt class="descname">values</tt><big>(</big><big>)</big><a class="reference external" href="http://github.com/astropy/astropy/tree/v0.2.4/astropy/io/fits.py#L1094" title="Push the Edit button on the next page"><span class="edit-on-github viewcode-link"> [edit on github]</span></a><a class="headerlink" href="#astropy.io.fits.Header.values" title="Permalink to this definition">¶</a></dt>
<dd><p>Returns a list of the values of all cards in the header.</p>
</dd></dl>
</dd></dl>
</div>
</div>
</div>
</div>
</div>
<div class="sphinxsidebar">
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<ul>
<li><a class="reference internal" href="#">Headers</a><ul>
<li><a class="reference internal" href="#header"><tt class="docutils literal"><span class="pre">Header</span></tt></a></li>
</ul>
</li>
</ul>
</div>
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