title: Set Pandas column values to an array
body: <p>I have the following problem:
  I have a dataframe like this one:</p>
  
  <pre><code>   col1   col2   col3
  0   2       5      4
  1   4       3      5
  2   6       2      7 
  </code></pre>
  
  <p>Now I have an array for example a = [5,5,5] and i want to insert this array in col3 but only in specific rows (let's say 0 and 2) and obtain something like that:</p>
  
  <pre><code>   col1   col2   col3
  0   2       5    [5,5,5]
  1   4       3      5
  2   6       2    [5,5,5]
  </code></pre>
  
  <p>The problem is that when I try to do:</p>
  
  <pre><code> zip_df.at[[0,2],'col3'] = a 
  </code></pre>
  
  <p>I receive the following error <code>ValueError: Must have equal len keys and value when setting with an ndarray</code>. How can I solve this problem?</p>