title: Finding the mean of nuisance columns in DataFrame error
body: <pre><code>      id gender status dept  var1  var2  salary
  0   P001      M     FT   DS   2.0   8.0     NaN
  1   P002      F     PT   FS   3.0   NaN    54.0
  2   P003      M    NaN  AWS   5.0   5.0    59.0
  3   P004      F     FT  AWS   NaN   8.0   120.0
  4   P005      M     PT   DS   7.0  11.0    58.0
  5   P006      F     PT  NaN   1.0   NaN    75.0
  6   P007      M     FT   FS   NaN   NaN     NaN
  7   P008      F    NaN   FS  10.0   2.0   136.0
  8   P009      M     PT  NaN  14.0   3.0    60.0
  9   P010      F     FT   DS   NaN   7.0   125.0
  10  P011      M    NaN  AWS   6.0   9.0     NaN
  
  print(df.mean())
  
  FutureWarning: Dropping of nuisance columns in DataFrame reductions (with 'numeric_only=None') is deprecated; in a future version this will raise TypeError.  Select only valid columns before calling the reduction.
    print(df.mean())
  </code></pre>
  <p>when corrected my code as :</p>
  <pre><code>print(df.mean(numeric_only=True))
  </code></pre>
  <p>I solve it , without an error.</p>
  <p>Is there any other way to solve it ?</p>