Regex R lookbehind : <p>How can I find the <code>n</code> words before the <code>colon</code> in this string in <code>R</code>? I'm using <code>stringr</code> but would regular expressions would be prefered.</p>

<pre><code>Input on income economic activities: Small business, self-emp…
</code></pre>

<p>Thanks,
E.</p>
