Pandas dataframe and to_numeric: select column by index
<p>The question is probaly extremely dumb, but i hurt my brain figuring out what to do</p>

<p>There is a <code>pd.dataframe</code> with N columns. I need to select some columns, referring by index of a column, then convert all values to numeric and rewrite that column in my <code>dataframe</code></p>

<p>I've done it by column name reference (like <code>df['a'] = pd.to_numeric(df['a'])</code> but stuck with indices (like <code>df[1] = pd.to_numeric(df[1])</code></p>

<p>What is the right way in this situation to <code>dataframe</code> column referencing? (python 2.7)</p>