<?xml version="1.0" encoding="ascii"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN"
"DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head>
<title>pygrib.open</title>
<link rel="stylesheet" href="epydoc.css" type="text/css" />
<script type="text/javascript" src="epydoc.js"></script>
</head>
<body bgcolor="white" text="black" link="blue" vlink="#204080"
alink="#204080">
<!-- ==================== NAVIGATION BAR ==================== -->
<table class="navbar" border="0" width="100%" cellpadding="0"
bgcolor="#a0c0ff" cellspacing="0">
<tr valign="middle">
<!-- Home link -->
<th> <a
href="pygrib-module.html">Home</a> </th>
<!-- Tree link -->
<th> <a
href="module-tree.html">Trees</a> </th>
<!-- Index link -->
<th> <a
href="identifier-index.html">Indices</a> </th>
<!-- Help link -->
<th> <a
href="help.html">Help</a> </th>
<th class="navbar" width="100%"></th>
</tr>
</table>
<table width="100%" cellpadding="0" cellspacing="0">
<tr valign="top">
<td width="100%">
<span class="breadcrumbs">
<a href="pygrib-module.html">Module pygrib</a> ::
Class open
</span>
</td>
<td>
<table cellpadding="0" cellspacing="0">
<!-- hide/show private -->
</table>
</td>
</tr>
</table>
<!-- ==================== TYPE DESCRIPTION ==================== -->
<h1 class="epydoc">type open</h1><p class="nomargin-top"></p>
<pre class="base-tree">
object --+
|
<strong class="uidshort">open</strong>
</pre>
<hr />
<p>open(filename)</p>
<p>returns GRIB file iterator object given GRIB filename. When iterated,
returns instances of the <a href="pygrib.gribmessage-class.html"
class="link">gribmessage</a> class. Behaves much like a python file
object, with <a href="pygrib.open-class.html#seek" class="link">seek</a>,
<a href="pygrib.open-class.html#tell" class="link">tell</a>, <a
href="pygrib.open-class.html#read" class="link">read</a> and <a
href="pygrib.open-class.html#close" class="link">close</a> methods,
except that offsets are measured in grib messages instead of bytes.
Additional methods include <a href="pygrib.open-class.html#rewind"
class="link">rewind</a> (like <code>seek(0)</code>), <a
href="pygrib.open-class.html#message" class="link">message</a> (like
<code>seek(N-1)</code>; followed by <code>readline()</code>), and <a
href="pygrib.open-class.html#select" class="link">select</a> (filters
messages based on specified conditions). The <code>__call__</code>
method forwards to <a href="pygrib.open-class.html#select"
class="link">select</a>, and instances can be sliced with
<code>__getitem__</code> (returning lists of <a
href="pygrib.gribmessage-class.html" class="link">gribmessage</a>
instances). The position of the iterator is not altered by slicing with
<code>__getitem__</code>.</p>
<!-- ==================== INSTANCE METHODS ==================== -->
<a name="section-InstanceMethods"></a>
<table class="summary" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="table-header">
<td align="left" colspan="2" class="table-header">
<span class="table-header">Instance Methods</span></td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="__call__"></a><span class="summary-sig-name">__call__</span>(<span class="summary-sig-arg">...</span>)</span><br />
same as <a href="pygrib.open-class.html#select"
class="link">select</a></td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="__enter__"></a><span class="summary-sig-name">__enter__</span>(<span class="summary-sig-arg">...</span>)</span></td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="__exit__"></a><span class="summary-sig-name">__exit__</span>(<span class="summary-sig-arg">...</span>)</span></td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="__getitem__"></a><span class="summary-sig-name">__getitem__</span>(<span class="summary-sig-arg">x</span>,
<span class="summary-sig-arg">y</span>)</span><br />
x[y]</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a href="pygrib.open-class.html#__init__" class="summary-sig-name">__init__</a>(<span class="summary-sig-arg">filename</span>)</span><br />
x.__init__(...) initializes x; see help(type(x)) for signature</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="__iter__"></a><span class="summary-sig-name">__iter__</span>(<span class="summary-sig-arg">x</span>)</span><br />
iter(x)</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type">a new object with type S, a subtype of T</span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a href="pygrib.open-class.html#__new__" class="summary-sig-name">__new__</a>(<span class="summary-sig-arg">T</span>,
<span class="summary-sig-arg">S</span>,
<span class="summary-sig-arg">...</span>)</span></td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="__next__"></a><span class="summary-sig-name">__next__</span>(<span class="summary-sig-arg">...</span>)</span></td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="close"></a><span class="summary-sig-name">close</span>()</span><br />
close GRIB file, deallocate C structures associated with class
instance</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a href="pygrib.open-class.html#message" class="summary-sig-name">message</a>(<span class="summary-sig-arg">N</span>)</span><br />
retrieve N'th message in iterator.</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type">the next value, or raise StopIteration</span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="next"></a><span class="summary-sig-name">next</span>(<span class="summary-sig-arg">x</span>)</span></td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a href="pygrib.open-class.html#read" class="summary-sig-name">read</a>(<span class="summary-sig-arg">N</span>=<span class="summary-sig-default">None</span>)</span><br />
read N messages from current position, returning grib messages
instances in a list.</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a href="pygrib.open-class.html#readline" class="summary-sig-name">readline</a>()</span><br />
read one entire grib message from the file.</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="rewind"></a><span class="summary-sig-name">rewind</span>(<span class="summary-sig-arg">...</span>)</span><br />
rewind iterator (same as seek(0))</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="seek"></a><span class="summary-sig-name">seek</span>(<span class="summary-sig-arg">N</span>,
<span class="summary-sig-arg">from_what</span>=<span class="summary-sig-default">0</span>)</span><br />
advance iterator N grib messages from beginning of file (if
<code>from_what=0</code>), from current position (if
<code>from_what=1</code>) or from the end of file (if
<code>from_what=2</code>).</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a href="pygrib.open-class.html#select" class="summary-sig-name">select</a>(<span class="summary-sig-arg">**kwargs</span>)</span><br />
return a list of <a href="pygrib.gribmessage-class.html"
class="link">gribmessage</a> instances from iterator filtered by
kwargs.</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr>
<td><span class="summary-sig"><a name="tell"></a><span class="summary-sig-name">tell</span>(<span class="summary-sig-arg">...</span>)</span><br />
returns position of iterator (grib message number, 0 means iterator
is positioned at beginning of file).</td>
<td align="right" valign="top">
</td>
</tr>
</table>
</td>
</tr>
</table>
<!-- ==================== INSTANCE VARIABLES ==================== -->
<a name="section-InstanceVariables"></a>
<table class="summary" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="table-header">
<td align="left" colspan="2" class="table-header">
<span class="table-header">Instance Variables</span></td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<a name="messagenumber"></a><span class="summary-name">messagenumber</span><br />
The grib message number that the iterator currently points to (the
value returned by <a href="pygrib.open-class.html#tell"
class="link">tell</a>).
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<a name="messages"></a><span class="summary-name">messages</span><br />
The total number of grib messages in the file.
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<a name="name"></a><span class="summary-name">name</span><br />
The GRIB file which the instance represents.
</td>
</tr>
</table>
<!-- ==================== PROPERTIES ==================== -->
<a name="section-Properties"></a>
<table class="summary" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="table-header">
<td align="left" colspan="2" class="table-header">
<span class="table-header">Properties</span></td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<a name="closed"></a><span class="summary-name">closed</span>
</td>
</tr>
<tr>
<td width="15%" align="right" valign="top" class="summary">
<span class="summary-type"> </span>
</td><td class="summary">
<a name="has_multi_field_msgs"></a><span class="summary-name">has_multi_field_msgs</span>
</td>
</tr>
</table>
<!-- ==================== METHOD DETAILS ==================== -->
<a name="section-MethodDetails"></a>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr bgcolor="#70b0f0" class="table-header">
<td align="left" colspan="2" class="table-header">
<span class="table-header">Method Details</span></td>
</tr>
</table>
<a name="__init__"></a>
<div>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr><td>
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr valign="top"><td>
<h3 class="epydoc"><span class="sig"><span class="sig-name">__init__</span>(<span class="sig-arg">filename</span>)</span>
<br /><em class="fname">(Constructor)</em>
</h3>
</td><td align="right" valign="top"
>
</td>
</tr></table>
<p>x.__init__(...) initializes x; see help(type(x)) for signature</p>
<dl class="fields">
<dt>Overrides:
object.__init__
</dt>
</dl>
</td></tr></table>
</div>
<a name="__new__"></a>
<div>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr><td>
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr valign="top"><td>
<h3 class="epydoc"><span class="sig"><span class="sig-name">__new__</span>(<span class="sig-arg">T</span>,
<span class="sig-arg">S</span>,
<span class="sig-arg">...</span>)</span>
</h3>
</td><td align="right" valign="top"
>
</td>
</tr></table>
<dl class="fields">
<dt>Returns: a new object with type S, a subtype of T</dt>
<dt>Overrides:
object.__new__
</dt>
</dl>
</td></tr></table>
</div>
<a name="message"></a>
<div>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr><td>
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr valign="top"><td>
<h3 class="epydoc"><span class="sig"><span class="sig-name">message</span>(<span class="sig-arg">N</span>)</span>
</h3>
</td><td align="right" valign="top"
>
</td>
</tr></table>
<p>retrieve N'th message in iterator. same as seek(N-1) followed by
readline().</p>
<dl class="fields">
</dl>
</td></tr></table>
</div>
<a name="read"></a>
<div>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr><td>
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr valign="top"><td>
<h3 class="epydoc"><span class="sig"><span class="sig-name">read</span>(<span class="sig-arg">N</span>=<span class="sig-default">None</span>)</span>
</h3>
</td><td align="right" valign="top"
>
</td>
</tr></table>
<p>read N messages from current position, returning grib messages
instances in a list. If N=None, all the messages to the end of the file
are read. <code>pygrib.open(f).read()</code> is equivalent to
<code>list(pygrib.open(f))</code>, both return a list containing <a
href="pygrib.gribmessage-class.html" class="link">gribmessage</a>
instances for all the grib messages in the file <code>f</code>.</p>
<dl class="fields">
</dl>
</td></tr></table>
</div>
<a name="readline"></a>
<div>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr><td>
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr valign="top"><td>
<h3 class="epydoc"><span class="sig"><span class="sig-name">readline</span>()</span>
</h3>
</td><td align="right" valign="top"
>
</td>
</tr></table>
<p>read one entire grib message from the file. Returns a <a
href="pygrib.gribmessage-class.html" class="link">gribmessage</a>
instance, or None if an EOF is encountered.</p>
<dl class="fields">
</dl>
</td></tr></table>
</div>
<a name="select"></a>
<div>
<table class="details" border="1" cellpadding="3"
cellspacing="0" width="100%" bgcolor="white">
<tr><td>
<table width="100%" cellpadding="0" cellspacing="0" border="0">
<tr valign="top"><td>
<h3 class="epydoc"><span class="sig"><span class="sig-name">select</span>(<span class="sig-arg">**kwargs</span>)</span>
</h3>
</td><td align="right" valign="top"
>
</td>
</tr></table>
<p>return a list of <a href="pygrib.gribmessage-class.html"
class="link">gribmessage</a> instances from iterator filtered by kwargs.
If keyword is a container object, each grib message in the iterator is
searched for membership in the container. If keyword is a callable (has a
_call__ method), each grib message in the iterator is tested using the
callable (which should return a boolean). If keyword is not a container
object or a callable, each grib message in the iterator is tested for
equality.</p>
<p>Example usage:</p>
<pre class="py-doctest">
<span class="py-prompt">>>> </span><span class="py-keyword">import</span> pygrib
<span class="py-prompt">>>> </span>grbs = pygrib.open(<span class="py-string">'sampledata/gfs.grb'</span>)
<span class="py-prompt">>>> </span>selected_grbs=grbs.select(shortName=<span class="py-string">'gh'</span>,typeOfLevel=<span class="py-string">'isobaricInhPa'</span>,level=10)
<span class="py-prompt">>>> </span><span class="py-keyword">for</span> grb <span class="py-keyword">in</span> selected_grbs: grb
<span class="py-output">26:Geopotential height:gpm (instant):regular_ll:isobaricInhPa:level 10 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output"></span><span class="py-prompt">>>> </span><span class="py-comment"># the __call__ method does the same thing</span>
<span class="py-prompt">>>> </span>selected_grbs=grbs(shortName=<span class="py-string">'gh'</span>,typeOfLevel=<span class="py-string">'isobaricInhPa'</span>,level=10)
<span class="py-prompt">>>> </span><span class="py-keyword">for</span> grb <span class="py-keyword">in</span> selected_grbs: grb
<span class="py-output">26:Geopotential height:gpm (instant):regular_ll:isobaricInhPa:level 10 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output"></span><span class="py-prompt">>>> </span><span class="py-comment"># to select multiple specific key values, use containers (e.g. sequences)</span>
<span class="py-prompt">>>> </span>selected_grbs=grbs(shortName=[<span class="py-string">'u'</span>,<span class="py-string">'v'</span>],typeOfLevel=<span class="py-string">'isobaricInhPa'</span>,level=[10,50])
<span class="py-prompt">>>> </span><span class="py-keyword">for</span> grb <span class="py-keyword">in</span> selected_grbs: grb
<span class="py-output">193:u-component of wind:m s**-1 (instant):regular_ll:isobaricInhPa:level 50 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output">194:v-component of wind:m s**-1 (instant):regular_ll:isobaricInhPa:level 50 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output">199:u-component of wind:m s**-1 (instant):regular_ll:isobaricInhPa:level 10 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output">200:v-component of wind:m s**-1 (instant):regular_ll:isobaricInhPa:level 10 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output"></span><span class="py-prompt">>>> </span><span class="py-comment"># to select key values based on a conditional expression, use a function</span>
<span class="py-prompt">>>> </span>selected_grbs=grbs(shortName=<span class="py-string">'gh'</span>,level=<span class="py-keyword">lambda</span> l: l < 500 <span class="py-keyword">and</span> l >= 300)
<span class="py-prompt">>>> </span><span class="py-keyword">for</span> grb <span class="py-keyword">in</span> selected_grbs: grb
<span class="py-output">14:Geopotential height:gpm (instant):regular_ll:isobaricInhPa:level 45000 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output">15:Geopotential height:gpm (instant):regular_ll:isobaricInhPa:level 40000 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output">16:Geopotential height:gpm (instant):regular_ll:isobaricInhPa:level 35000 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span>
<span class="py-output">17:Geopotential height:gpm (instant):regular_ll:isobaricInhPa:level 30000 Pa:fcst time 72 hrs:from 200412091200:lo res cntl fcst</span></pre>
<dl class="fields">
</dl>
</td></tr></table>
</div>
<br />
<!-- ==================== NAVIGATION BAR ==================== -->
<table class="navbar" border="0" width="100%" cellpadding="0"
bgcolor="#a0c0ff" cellspacing="0">
<tr valign="middle">
<!-- Home link -->
<th> <a
href="pygrib-module.html">Home</a> </th>
<!-- Tree link -->
<th> <a
href="module-tree.html">Trees</a> </th>
<!-- Index link -->
<th> <a
href="identifier-index.html">Indices</a> </th>
<!-- Help link -->
<th> <a
href="help.html">Help</a> </th>
<th class="navbar" width="100%"></th>
</tr>
</table>
<table border="0" cellpadding="0" cellspacing="0" width="100%%">
<tr>
<td align="left" class="footer">
Generated by Epydoc 3.0.1
on Mon Oct 21 13:23:56 2013
</td>
<td align="right" class="footer">
<a target="mainFrame" href="http://epydoc.sourceforge.net"
>http://epydoc.sourceforge.net</a>
</td>
</tr>
</table>
<script type="text/javascript">
<!--
// Private objects are initially displayed (because if
// javascript is turned off then we want them to be
// visible); but by default, we want to hide them. So hide
// them unless we have a cookie that says to show them.
checkCookie();
// -->
</script>
</body>
</html>
