Selecting column location before modifying its data in Python Panda data frame

Question

Panda beginner here.

I have below dataframe

Column1	Column2	Column3	Column12	Column13
A	C	E	G	I
B	D	F	H	J

I want to modify data if the column satisfy certain conditions. For example

If column.contains('2', case=False)

then I want to change the data value to 3

Expected result:

Column1	Column2	Column3	Column12	Column13
A	3	E	3	I
B	3	F	3	J

Answer 1

Use str.contains with boolean indexing:

df.loc[:, df.columns.str.contains('2', case=False)] = 3

NB. case does not matter for 2.

output:

  Column1 Column2 Column3 Column12 Column13
0       A       3       E        3        I
1       B       3       F        3        J