pandas, multiply all the numeric values in the data frame by a constant

Question

How to multiply all the numeric values in the data frame by a constant without having to specify column names explicitly? Example:

In [13]: df = pd.DataFrame         


        

Answer 1

you can use select_dtypes() including number dtype or excluding all columns of object and datetime64 dtypes:

Demo:

In [162]: df
Out[162]:
  col1  col2  col3       date
0    A     1    30 2016-01-01
1    B     2    10 2016-01-02
2    C     3    20 2016-01-03

In [163]: df.dtypes
Out[163]:
col1            object
col2             int64
col3             int64
date    datetime64[ns]
dtype: object

In [164]: df.select_dtypes(exclude=['object', 'datetime']) * 3
Out[164]:
   col2  col3
0     3    90
1     6    30
2     9    60

or a much better solution (c) ayhan:

df[df.select_dtypes(include=['number']).columns] *= 3

From docs:

To select all numeric types use the numpy dtype numpy.number