title: Wordcloud with a specific shape
body: <p>Suppose, I have a dataframe which contains some words with their frequencies. I want to create a wordcloud in R with the words inside the shape of a logo, for example, the twitter logo just like this:
  <a href="https://i.stack.imgur.com/TNj0R.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/TNj0R.jpg" alt="enter image description here" /></a></p>
  <p>For the wordcloud, there is a package named <code>wordcloud2</code> and running the demo only gives a square image of the words. How would I add a specific image of my choice to be the shape of the wordcloud?</p>
  <p><code>wordcloud2(demoFreq)</code> only ouputs a square.</p>