title: Getting multiple matches per string for a vector of strings
body: <p>I have some text that looks as follows:</p>
  
  <pre><code>P17-Nationalist Revolutionary Movement-Free Bolivia Movement (Movimiento Nacionalista Revolucionario [MNR] - Movimiento Bolivia Libre [MBL] [MNR-MBL])
  P18-Socialist Party (Partido Socialista [PS])
  P19-Liberty and Justice (Libertad y Justicia [LJ])
  
  All_Election_Parties &lt;- readr::read_lines("All_Election_Parties.txt") 
  </code></pre>
  
  <p>The code: <code>str_match_all(entry, "(?&lt;=\\[).+?(?=\\])")</code> creates a list of matches. </p>
  
  <pre><code>[1] [MBL] 
  [2] [MNR-MBL]
  [3] [PS]
  [4] [LJ]
  </code></pre>
  
  <p>What I want however is for it to create a list/column/vector with a vector/list of all matches for each string. Something like this:</p>
  
  <pre><code>[1] [MBL] [MNR-MBL]
  [2] [PS]
  [3] [LJ]
  </code></pre>
  
  <p>How do I do that?</p>