add new column to dataframe with values matching the keys with existing column in dataframe in python

Question

fairly new to python and pandas/numpy. I have a data frame and a dictionary. I need to add a new column in the data frame where the values would be the values from dictionary for the matching dictionary keys with the existing column in data frame. and have empty string for non matching values.

	Name	Fonder	Year
0	company1	person1	1999
1	company2	person2	2000
2	company3	person3	2001
3	company4	person4	2002
4	company5	person5	2003

col_dict = {'company2': 'abc', 'company4': 'xyz',}

I want the following

	Name	Fonder	Year	new_col
0	company1	person1	1999
1	company2	person2	2000	abc
2	company3	person3	2001
3	company4	person4	2002	xyz
4	company5	person5	2003

score 0 · Accepted Answer · answered Jan 23 '23 at 07:09

You can use map:

df['new_col'] = df['Name'].map(col_dict).fillna('')
print(df)

# Output
       Name   Fonder  Year new_col
0  company1  person1  1999        
1  company2  person2  2000     abc
2  company3  person3  2001        
3  company4  person4  2002     xyz
4  company5  person5  2003

add new column to dataframe with values matching the keys with existing column in dataframe in python

1 Answers1