Pandas: change multiple level column name to one level

Question

I have a dataframe with two-level column names as:

ID Value
A B
----------------
1 6
2 5
3 4
4 3
5 2
6 1

I want to change the column head with:

column_mapping = {
 ('ID', 'A') : 'ID:A',
 ('Value', 'B'): 'Value:B'
}

I tried rename:

df.rename(columns=column_mapping, inplace=True)

which does not work. Any idea how?

Answer 1

Try:

df.columns = df.columns.map(":".join)
print(df)

Prints:

 ID:A Value:B
0 1.0 6.0
1 2.0 5.0
2 3.0 4.0
3 4.0 3.0
4 5.0 2.0
5 6.0 1.0