问将空值保留在熊猫dataframe列中，同时将类型分配给它们

EN

df.loc[df.ViewersStart.notnull(),'ViewersStart'] = df.loc[df.ViewersStart.notnull(),'ViewersStart'].astype('int64')

df = pd.DataFrame({'ViewersStart':['1','5',6,np.nan,'12']})
>>> df
  ViewersStart
0            1
1            5
2            6
3          NaN
4           12

# Notice that your column is a mix of strings, ints and NaN
>>> df.values
array([['1'],
       ['5'],
       [6],
       [nan],
       ['12']], dtype=object)

df.loc[df.ViewersStart.notnull(),'ViewersStart'] = df.loc[df.ViewersStart.notnull(),'ViewersStart'].astype('int64')

>>> df
  ViewersStart
0            1
1            5
2            6
3          NaN
4           12

# Notice that all non-null values are now ints
>>> df.values
array([[1],
       [5],
       [6],
       [nan],
       [12]], dtype=object)