Using Pandas to_numeric() in Azure Machine Learning Studio
What’s new in Pandas v0.17.0


  DataFrame.convert_objects has been deprecated in favor of
  type-specific functions pd.to_datetime, pd.to_timestamp and
  pd.to_numeric (new in 0.17.0) (GH11133).


So for Pandas versions &lt; 0.17.0 you can and should use: df.convert_objects(convert_numeric=True)

Demo:

In [213]: x = pd.DataFrame({'a':['11', 'aaa', '0', np.nan, '123']})

In [214]: x
Out[214]:
     a
0   11
1  aaa
2    0
3  NaN
4  123

In [215]: x.dtypes
Out[215]:
a    object
dtype: object

In [216]: x = x.convert_objects(convert_numeric=True)

In [217]: x
Out[217]:
       a
0   11.0
1    NaN
2    0.0
3    NaN
4  123.0

In [218]: x.dtypes
Out[218]:
a    float64
dtype: object