Pandas Get First Element of Each Tuple in Cell

Question

Given the following data frame:

import pandas as pd
df=pd.DataFrame({'A':['a','b','c'],
                 'B':[[[1,2],[3,4],[5,6]],[[1,2],[3,4],[5,6]],[[1,2],[3,4],[5,6]]]})
df

    A               B
0   a   [[1, 2], [3, 4], [5, 6]]
1   b   [[1, 2], [3, 4], [5, 6]]
2   c   [[1, 2], [3, 4], [5, 6]]

I'd like to create a new column ('C') containing the first value in each element of the tuple of column B like this:

    A               B                 C
0   a   [[1, 2], [3, 4], [5, 6]]   [1,3,5]
1   b   [[1, 2], [3, 4], [5, 6]]   [1,3,5]
2   c   [[1, 2], [3, 4], [5, 6]]   [1,3,5]

So far, I've tried:

df['C']=df['B'][0]

...but that only returns the first tuple ([1, 2]).

Thanks in advance!

Beau

won't df['B'].apply(lambda x: [e[0] for e in x]) work? OK just re-read it, see updated comment – Eliason

Yes, indeed. Are you going to post as an answer? – Beau

No need Alberto's answer is what I would've posted – Eliason

Answer 1

df['C'] = df['B'].apply(lambda x: [y[0] for y in x])

Arms

Answer 2

This works for me -

df['C'] = df['B'].str[0]

Eveleen

This worked for me as well, getting a int value out of a tuple[int,int,int] – Nerve

Answer 3

try this:

df['C'] =   df["B"].apply(lambda x : [y[0] for y in list(x)])

Libel