CODEWITHSUNDEEP
pythonpandasdataframe
JohnnieL
JohnnieL

Reputation: 1231

python pandas add multiple columns not existing in another list

I have a dataframe whose column names are a subset of the index values of another dataframe.

I would like to add to the initial dataframe empty columns that exists in the second index but do not exist as column names in the first. I have solved this using the following loop but wonder is there a smarter way to do this using, for example, assign or append(axis=1)?

My example below with the output it produces (the correct desired result)

Thanks

import pandas as pd
df_matrix = pd.DataFrame([(1, 2),
                   (3, 4)],
                  index=[['a','b']],
                  columns=('value_1','value_3'))

df_matrix

value_1 value_3
a 1 2
b 3 4 
df_column = pd.DataFrame({'value':[11, 22, 33, 44]}, index=['value_1','value_2','value_3','value_4'])

df_column

value
value_1 11
value_2 22
value_3 33
value_4 44 
for index, row in df_column.iterrows():
    if index not in df_matrix.columns:
        df_matrix[index]=0

updated df_matrix

value_1 value_3 value_2 value_4
a 1 2 0 0
b 3 4 0 0

Upvotes: 1

Views: 389

Answers (1)

Chris
Chris

Reputation: 16172

This would essentially do what you want without the loop.

df_matrix[[x for x in df_column.index if x not in df_matrix.columns]] = 0

 value_1  value_3   value_2 value_4
a   1          2        0      0
b   3          4        0      0

Upvotes: 3

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