R - subset data frame column using names in vector list
<p>Is it possible to subset data frame columns  (into new df) using column names stored in the array of column names - like in c("col1", "col9", "col6")? I know I can reference one column in df using df[[colname]] syntax but it does not let me do it for multiple columns:</p>

<pre><code>df
   X1 X2 X3
1:  a  1  3
2:  b  5  3
3:  a  3  4
4:  c  6  5
5:  c  2  2

cnm&lt;-c("X2","X3")

df[[cnm]]
</code></pre>

<blockquote>
  <p>Error in .subset2(x, i, exact = exact) : subscript out of bounds</p>
</blockquote>

<p>thanks</p>