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<h2 class="chapter">27 Sets</h2>
<p>Octave has a limited number of functions for managing sets of data, where a
set is defined as a collection of unique elements. In Octave a set is
represented as a vector of numbers.
<!-- unique scripts/set/unique.m -->
<p><a name="doc_002dunique"></a>
<div class="defun">
— Function File: <b>unique</b> (<var>x</var>)<var><a name="index-unique-2679"></a></var><br>
— Function File: <b>unique</b> (<var>x, "rows"</var>)<var><a name="index-unique-2680"></a></var><br>
— Function File: <b>unique</b> (<var><small class="dots">...</small>, "first"</var>)<var><a name="index-unique-2681"></a></var><br>
— Function File: <b>unique</b> (<var><small class="dots">...</small>, "last"</var>)<var><a name="index-unique-2682"></a></var><br>
— Function File: [<var>y</var>, <var>i</var>, <var>j</var>] = <b>unique</b> (<var><small class="dots">...</small></var>)<var><a name="index-unique-2683"></a></var><br>
<blockquote><p>Return the unique elements of <var>x</var>, sorted in ascending order.
If the input <var>x</var> is a vector then the output is also a vector with the
same orientation (row or column) as the input. For a matrix input the
output is always a column vector. <var>x</var> may also be a cell array of
strings.
<p>If the optional argument <code>"rows"</code> is supplied, return the unique
rows of <var>x</var>, sorted in ascending order.
<p>If requested, return index vectors <var>i</var> and <var>j</var> such that
<code>x(i)==y</code> and <code>y(j)==x</code>.
<p>Additionally, if <var>i</var> is a requested output then one of <code>"first"</code> or
<code>"last"</code> may be given as an input. If <code>"last"</code> is specified,
return the highest possible indices in <var>i</var>, otherwise, if <code>"first"</code>
is specified, return the lowest. The default is <code>"last"</code>.
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<p class="noindent"><strong>See also:</strong> <a href="doc_002dunion.html#doc_002dunion">union</a>, <a href="doc_002dintersect.html#doc_002dintersect">intersect</a>, <a href="doc_002dsetdiff.html#doc_002dsetdiff">setdiff</a>, <a href="doc_002dsetxor.html#doc_002dsetxor">setxor</a>, <a href="doc_002dismember.html#doc_002dismember">ismember</a>.
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