I have a pandas dataframe like so:
col1 col2 col3
1 8 6
2 9 5
5 3 9
Now I want to add a new column with values from a list for each and every row of my dataframe. So if my list is like so:
lst = ["a", "b","c"]
then I want the final dataframe to be like:
col1 col2 col3 name
1 8 6 a
1 8 6 b
1 8 6 c
2 9 5 a
2 9 5 b
2 9 5 c
5 3 9 a
5 3 9 b
5 3 9 c
First idea is use Index.repeat by length of list and then append new column with numpy.tile:
lst = ["a", "b","c"]
df1 = (df.loc[df.index.repeat(len(lst))]
.assign(name=np.tile(lst, len(df)))
.reset_index(drop=True))
print (df1)
col1 col2 col3 name
0 1 8 6 a
1 1 8 6 b
2 1 8 6 c
3 2 9 5 a
4 2 9 5 b
5 2 9 5 c
6 5 3 9 a
7 5 3 9 b
8 5 3 9 c
Or use cross join with DataFrame from list:
df1 = df.assign(a=1).merge(pd.DataFrame({'name':lst, 'a':1}), on='a').drop('a', axis=1)
print (df1)
col1 col2 col3 name
0 1 8 6 a
1 1 8 6 b
2 1 8 6 c
3 2 9 5 a
4 2 9 5 b
5 2 9 5 c
6 5 3 9 a
7 5 3 9 b
8 5 3 9 c
