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<p>
Next: <a href="Cell-Arrays-of-Strings.html" accesskey="n" rel="next">Cell Arrays of Strings</a>, Previous: <a href="Creating-Cell-Arrays.html" accesskey="p" rel="prev">Creating Cell Arrays</a>, Up: <a href="Cell-Arrays.html" 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" title="Index" rel="index">Index</a>]</p>
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<h4 class="subsection" id="Indexing-Cell-Arrays-1"><span>6.3.3 Indexing Cell Arrays<a class="copiable-link" href="#Indexing-Cell-Arrays-1"> ¶</a></span></h4>
<p>As shown in see <a class="pxref" href="Basic-Usage-of-Cell-Arrays.html">Basic Usage of Cell Arrays</a> elements can be
extracted from cell arrays using the ‘<samp class="samp">{</samp>’ and ‘<samp class="samp">}</samp>’
operators. If you want to extract or access subarrays which are still
cell arrays, you need to use the ‘<samp class="samp">(</samp>’ and ‘<samp class="samp">)</samp>’ operators. The
following example illustrates the difference:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">c = {"1", "2", "3"; "x", "y", "z"; "4", "5", "6"};
c{2,3}
⇒ ans = z
c(2,3)
⇒ ans =
{
[1,1] = z
}
</pre></div></div>
<p>So with ‘<samp class="samp">{}</samp>’ you access elements of a cell
array, while with ‘<samp class="samp">()</samp>’ you access a sub array of a cell
array.
</p>
<p>Using the ‘<samp class="samp">(</samp>’ and ‘<samp class="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 class="code">0</code>
with the following command:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">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></div>
<p>Note, that the above can also be achieved like this:
</p>
<div class="example">
<pre class="example-preformatted">c(:, [1, 3]) = 0;
</pre></div>
<p>Here, the scalar ‘<samp class="samp">0</samp>’ is automatically promoted to
cell array ‘<samp class="samp">{0}</samp>’ and then assigned to the subarray of <code class="code">c</code>.
</p>
<p>To give another example for indexing cell arrays with ‘<samp class="samp">()</samp>’, you
can exchange the first and the second row of a cell array as in the
following command:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">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></div>
<p>Accessing multiple elements of a cell array with the ‘<samp class="samp">{</samp>’ and
‘<samp class="samp">}</samp>’ operators will result in a comma-separated list of all the
requested elements (see <a class="pxref" href="Comma_002dSeparated-Lists.html">Comma-Separated Lists</a>). Using the
‘<samp class="samp">{</samp>’ and ‘<samp class="samp">}</samp>’ operators the first two rows in the above
example can be swapped back like this:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">[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></div>
<p>As for struct arrays and numerical arrays, the empty matrix ‘<samp class="samp">[]</samp>’
can be used to delete elements from a cell array:
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">x = {"1", "2"; "3", "4"};
x(1, :) = []
⇒ x =
{
[1,1] = 3
[1,2] = 4
}
</pre></div></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">
<div class="group"><pre class="example-preformatted">x = {"1", "2"; "3", "4"};
x(1, :) = {[]}
⇒ x =
{
[1,1] = [](0x0)
[2,1] = 3
[1,2] = [](0x0)
[2,2] = 4
}
</pre></div></div>
<p>The indexing operations operate on the cell array and not on the objects
within the cell array. By contrast, <code class="code">cellindexmat</code> applies matrix
indexing to the objects within each cell array entry and returns the requested
values.
</p>
<a class="anchor" id="XREFcellindexmat"></a><span style="display:block; margin-top:-4.5ex;"> </span>
<dl class="first-deftypefn">
<dt class="deftypefn" id="index-cellindexmat"><span><code class="def-type"><var class="var">y</var> =</code> <strong class="def-name">cellindexmat</strong> <code class="def-code-arguments">(<var class="var">x</var>, <var class="var">varargin</var>)</code><a class="copiable-link" href="#index-cellindexmat"> ¶</a></span></dt>
<dd><p>Perform indexing of matrices in a cell array.
</p>
<p>Given a cell array of matrices <var class="var">x</var>, this function computes
</p>
<div class="example">
<div class="group"><pre class="example-preformatted">Y = cell (size (X));
for i = 1:numel (X)
Y{i} = X{i}(varargin{1}, varargin{2}, ..., varargin{N});
endfor
</pre></div></div>
<p>The indexing arguments may be scalar (<code class="code">2</code>), arrays (<code class="code">[1, 3]</code>),
ranges (<code class="code">1:3</code>), or the colon operator (<code class="code">":"</code>). However, the
indexing keyword <code class="code">end</code> is not available.
</p>
<p><strong class="strong">See also:</strong> <a class="ref" href="Creating-Cell-Arrays.html#XREFcellslices">cellslices</a>, <a class="ref" href="Function-Application.html#XREFcellfun">cellfun</a>.
</p></dd></dl>
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