title: how to replace an entire column on Pandas.DataFrame
body: <p>I would like to replace an entire column on a Pandas DataFrame with another column taken from another DataFrame, an example will clarify what I am looking for</p>
  <pre><code>import pandas as pd
  dic = {'A': [1, 4, 1, 4], 'B': [9, 2, 5, 3], 'C': [0, 0, 5, 3]}
  df = pd.DataFrame(dic)
  </code></pre>
  <p>df is</p>
  <pre><code>'A' 'B' 'C'
   1   9   0
   4   2   0
   1   5   5
   4   3   3
  </code></pre>
  <p>Now I have another dataframe called <code>df1</code> with a column <code>&quot;E&quot;</code> that is</p>
  <pre><code>df1['E'] = [ 4, 4, 4, 0]
  </code></pre>
  <p>and I would like to replace column <code>&quot;B&quot;</code> of df with column <code>&quot;E&quot;</code> of <code>df1</code></p>
  <pre><code>'A' 'E' 'C'
   1   4   0
   4   4   0
   1   4   5
   4   0   3
  </code></pre>
  <p>I tried to use the <code>.replace()</code> method in many ways but I didn't get anything good. Can you help me?</p>