title: Split a dataframe column's list into two dataframe columns
body: <p>I'm effectively trying to do a text-to-columns (from MS Excel) action, but in Pandas.</p>
  
  <p>I have a dataframe that contains values like: 1_1, 2_1, 3_1, and I only want to take the values to the right of the underscore. I figured out how to split the string, which gives me a list of the broken up string, but I don't know how to break that out into different dataframe columns.</p>
  
  <p>Here is my code:</p>
  
  <pre><code>import pandas as pd
  
  test = pd.DataFrame(['1_1','2_1','3_1'])
  test.columns = ['values']
  
  test = test['values'].str.split('_')
  </code></pre>
  
  <p>I get something like: [1, 1], [2, 1], [3, 1].</p>
  
  <p>What I'm trying to get is two separate columns:</p>
  
  <p>col1: 1, 2, 3
  col2: 1, 1 ,1</p>
  
  <p>Thoughts? Thanks in advance for your help</p>