Replace last comma in character with " &" : <p>I have many different characters which have the following structure:</p>

<pre><code># Example
x &lt;- "char1, char2, char3"
</code></pre>

<p>I want to remove the last comma of this character with " &amp;", i.e. the desired output should look as follows:</p>

<pre><code># Desired output
"char1, char2 &amp; char3"
</code></pre>

<p>How could I replace the last comma of a character with " &amp;"?</p>
