title: Pandas: fillna every columns with some value
body: <p>I have dataframe and there are <code>NaN</code> values:</p>
  
  <pre><code>col1   col2    col3
  234    NaN     1
  NaN    NaN     18
  9      2       NaN
  </code></pre>
  
  <p>I have list with values [12, 15, 3] and I need to fill this columns:</p>
  
  <p>Desire output</p>
  
  <pre><code>col1   col2   col3
  234    15     1
  12     15     18
  9      2      3
  </code></pre>
  
  <p>I can do it with </p>
  
  <pre><code>for (col, mean) in zip(df.columns, means):
      df[col].fillna(mean, inplace=True)
  </code></pre>
  
  <p>But is any way to do it without loop?</p>