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(This article was first published on <strong><a href="https://g4greetz.wordpress.com/2017/03/01/match-function-in-r/"> R – Greetz to Geeks</a></strong>, and kindly contributed to <a rel="nofollow" href="https://www.r-bloggers.com/">R-bloggers)</a> </div>
<p>The<strong> match()</strong> function returns a vector of the position of first occurrence of the vector1 in vector2. If the element of the vector1 does not exist in vector2, NA is returned.</p>
<p><strong>Syntax: <span>match(vector1, vector2, nomatch = NA_integer_, incomparables = NULL)</span></strong></p>
<p><span>vector1</span>: vector, the values to be matched<br>
<span>vector2</span>: vector, the values to be matched against<br>
<span>nomatch</span>: the value which should be returned when no match is found<br>
<span>incomparables</span>: the vector of values that cannot be matched.</p>
<p>By default the nomatch argument will return NA in case the match is not found in vector2.</p>
<p>According to the <a target="_blank" rel="nofollow" href="https://stat.ethz.ch/R-manual/R-devel/library/base/html/match.html">R Documentation</a>  the <strong>%in%</strong> operator is equivalent to match(). It is a logical vector which indicates whether a match was located for vector1 in vector2. The result value will be either TRUE or FALSE but never NA. So the %in% operator can be useful in if conditions.</p>
<p><strong>Syntax:</strong> <strong><span>vector1 %n% vector2</span></strong></p>
<p><strong>Examples:</strong></p>
<pre>
print(match(5, c(1,2,9,5,3,6,7,4,5)))
[1] 4
</pre>
<pre>
5 %in% c(1,2,9,5,3,6,7,4,5)
[1] TRUE
</pre>
<pre>
8 %in% c(1,2,9,5,3,6,7,4,5)
[1] FALSE
</pre>
<pre>
> v1 &lt;- c(&quot;a1&quot;,&quot;b2&quot;,&quot;c1&quot;,&quot;d2&quot;)
> v2 &lt;- c(&quot;g1&quot;,&quot;x2&quot;,&quot;d2&quot;,&quot;e2&quot;,&quot;f1&quot;,&quot;a1&quot;,&quot;c2&quot;,&quot;b2&quot;,&quot;a2&quot;)
> x &lt;- match(v1,v2)
> x
[1] 6 8 NA 3
</pre>
<pre>
> v1 &lt;- c(&quot;a1&quot;,&quot;b2&quot;,&quot;c1&quot;,&quot;d2&quot;)
> v2 &lt;- c(&quot;g1&quot;,&quot;x2&quot;,&quot;d2&quot;,&quot;e2&quot;,&quot;f1&quot;,&quot;a1&quot;,&quot;c2&quot;,&quot;b2&quot;,&quot;a2&quot;)
> v1 %in% v2
[1] TRUE TRUE FALSE TRUE
</pre>
<pre>
> v1 &lt;- c(&quot;a1&quot;,&quot;b2&quot;,&quot;c1&quot;,&quot;d2&quot;)
> v2 &lt;- c(&quot;g1&quot;,&quot;x2&quot;,&quot;d2&quot;,&quot;e2&quot;,&quot;f1&quot;,&quot;a1&quot;,&quot;c2&quot;,&quot;b2&quot;,&quot;a2&quot;)
> x &lt;- match(v1,v2, nomatch = 0)
> x
[1] 6 8 0 3
</pre>
<pre>
> v1 &lt;- c(&quot;a1&quot;,&quot;b2&quot;,&quot;c1&quot;,&quot;d2&quot;)
> v2 &lt;- c(&quot;g1&quot;,&quot;x2&quot;,&quot;d2&quot;,&quot;e2&quot;,&quot;f1&quot;,&quot;a1&quot;,&quot;c2&quot;,&quot;b2&quot;,&quot;a2&quot;)
> x &lt;- match(v1,v2, nomatch = 0, incomparables = &quot;a1&quot;)
> x
[1] 0 8 0 3
</pre>
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