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<a name="Indexing-Cell-Arrays"></a>
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<p>
Next: <a href="Cell-Arrays-of-Strings.html#Cell-Arrays-of-Strings" accesskey="n" rel="next">Cell Arrays of Strings</a>, Previous: <a href="Creating-Cell-Arrays.html#Creating-Cell-Arrays" accesskey="p" rel="prev">Creating Cell Arrays</a>, Up: <a href="Cell-Arrays.html#Cell-Arrays" accesskey="u" rel="up">Cell Arrays</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
</div>
<hr>
<a name="Indexing-Cell-Arrays-1"></a>
<h4 class="subsection">6.3.3 Indexing Cell Arrays</h4>
<p>As shown in see <a href="Basic-Usage-of-Cell-Arrays.html#Basic-Usage-of-Cell-Arrays">Basic Usage of Cell Arrays</a> elements can be
extracted from cell arrays using the ‘<samp>{</samp>’ and ‘<samp>}</samp>’
operators. If you want to extract or access subarrays which are still
cell arrays, you need to use the ‘<samp>(</samp>’ and ‘<samp>)</samp>’ operators. The
following example illustrates the difference:
</p>
<div class="example">
<pre class="example">c = {"1", "2", "3"; "x", "y", "z"; "4", "5", "6"};
c{2,3}
⇒ ans = z
c(2,3)
⇒ ans =
{
[1,1] = z
}
</pre></div>
<p>So with ‘<samp>{}</samp>’ you access elements of a cell
array, while with ‘<samp>()</samp>’ you access a sub array of a cell
array.
</p>
<p>Using the ‘<samp>(</samp>’ and ‘<samp>)</samp>’ operators, indexing works for cell
arrays like for multi-dimensional arrays. As an example, all the rows
of the first and third column of a cell array can be set to <code>0</code>
with the following command:
</p>
<div class="example">
<pre class="example">c(:, [1, 3]) = {0}
⇒ =
{
[1,1] = 0
[2,1] = 0
[3,1] = 0
[1,2] = 2
[2,2] = y
[3,2] = 5
[1,3] = 0
[2,3] = 0
[3,3] = 0
}
</pre></div>
<p>Note, that the above can also be achieved like this:
</p>
<div class="example">
<pre class="example">c(:, [1, 3]) = 0;
</pre></div>
<p>Here, the scalar ‘<samp>0</samp>’ is automatically promoted to
cell array ‘<samp>{0}</samp>’ and then assigned to the subarray of <code>c</code>.
</p>
<p>To give another example for indexing cell arrays with ‘<samp>()</samp>’, you
can exchange the first and the second row of a cell array as in the
following command:
</p>
<div class="example">
<pre class="example">c = {1, 2, 3; 4, 5, 6};
c([1, 2], :) = c([2, 1], :)
⇒ =
{
[1,1] = 4
[2,1] = 1
[1,2] = 5
[2,2] = 2
[1,3] = 6
[2,3] = 3
}
</pre></div>
<p>Accessing multiple elements of a cell array with the ‘<samp>{</samp>’ and
‘<samp>}</samp>’ operators will result in a comma-separated list of all the
requested elements (see <a href="Comma-Separated-Lists.html#Comma-Separated-Lists">Comma Separated Lists</a>). Using the
‘<samp>{</samp>’ and ‘<samp>}</samp>’ operators the first two rows in the above
example can be swapped back like this:
</p>
<div class="example">
<pre class="example">[c{[1,2], :}] = deal (c{[2, 1], :})
⇒ =
{
[1,1] = 1
[2,1] = 4
[1,2] = 2
[2,2] = 5
[1,3] = 3
[2,3] = 6
}
</pre></div>
<p>As for struct arrays and numerical arrays, the empty matrix ‘<samp>[]</samp>’
can be used to delete elements from a cell array:
</p>
<div class="example">
<pre class="example">x = {"1", "2"; "3", "4"};
x(1, :) = []
⇒ x =
{
[1,1] = 3
[1,2] = 4
}
</pre></div>
<p>The following example shows how to just remove the contents of cell
array elements but not delete the space for them:
</p>
<div class="example">
<pre class="example">x = {"1", "2"; "3", "4"};
x(1, :) = {[]}
⇒ x =
{
[1,1] = [](0x0)
[2,1] = 3
[1,2] = [](0x0)
[2,2] = 4
}
</pre></div>
<p>The indexing operations operate on the cell array and not on the objects
within the cell array. By contrast, <code>cellindexmat</code> applies matrix
indexing to the objects within each cell array entry and returns the requested
values.
</p>
<a name="XREFcellindexmat"></a><dl>
<dt><a name="index-cellindexmat"></a><em><var>y</var> =</em> <strong>cellindexmat</strong> <em>(<var>x</var>, <var>varargin</var>)</em></dt>
<dd><p>Perform indexing of matrices in a cell array.
</p>
<p>Given a cell array of matrices <var>x</var>, this function computes
</p>
<div class="example">
<pre class="example">Y = cell (size (X));
for i = 1:numel (X)
Y{i} = X{i}(varargin{1}, varargin{2}, …, varargin{N});
endfor
</pre></div>
<p>The indexing arguments may be scalar (<code>2</code>), arrays (<code>[1, 3]</code>),
ranges (<code>1:3</code>), or the colon operator (<code>":"</code>). However, the
indexing keyword <code>end</code> is not available.
</p>
<p><strong>See also:</strong> <a href="Creating-Cell-Arrays.html#XREFcellslices">cellslices</a>, <a href="Function-Application.html#XREFcellfun">cellfun</a>.
</p></dd></dl>
<hr>
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<p>
Next: <a href="Cell-Arrays-of-Strings.html#Cell-Arrays-of-Strings" accesskey="n" rel="next">Cell Arrays of Strings</a>, Previous: <a href="Creating-Cell-Arrays.html#Creating-Cell-Arrays" accesskey="p" rel="prev">Creating Cell Arrays</a>, Up: <a href="Cell-Arrays.html#Cell-Arrays" accesskey="u" rel="up">Cell Arrays</a> [<a href="index.html#SEC_Contents" title="Table of contents" rel="contents">Contents</a>][<a href="Concept-Index.html#Concept-Index" title="Index" rel="index">Index</a>]</p>
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