Pandas DataFrame: create a column from a list inside a column

Question

I'm having the pandas DataFrame 'test_df':

email                      my_list
[email protected]          [1,9,3,5]
[email protected]          [6,3,3,15]
[email protected]          [7,7,2,5]
[email protected]          [5,5,5,5]

How can I have this following DataFrame (take the first 2 elem of 'my_list'):

email                      col1             col2             
[email protected]          1                9        
[email protected]          6                3
[email protected]          7                7
[email protected]          5                5

I tried:

test_df['col1'] = test_df['my_list'][0]
test_df['col2'] = test_df['my_list'][1]

But it's not working

What is the element type of my_list? IOW, what does type(test_df.my_list[0]) return? — DSM
– DSM, Commented Jan 12, 2015 at 5:16
thanks for your answer @DSM type(test_df.my_list[0]) <type 'list'> — woshitom
– woshitom, Commented Jan 12, 2015 at 5:22

Community · Accepted Answer · 2017-05-23 11:53:35Z

3

I asked a related question here, although I wanted to go a bit beyond expanding the lists into columns so the answers are more complicated than what you need. In your case, you can just do:

# Using my own example data since it's a bit tough to copy-paste
# a printed table and have the lists show up as lists
df = pd.DataFrame({'email': ['[email protected]', '[email protected]'], 
                   'lists': [[1, 9, 3, 5], [6, 3, 3, 15]]})
df
Out[14]: 
           email          lists
0  [email protected]   [1, 9, 3, 5]
1  [email protected]  [6, 3, 3, 15]

objs = [df, pd.DataFrame(df['lists'].tolist()).iloc[:, :2]]
pd.concat(objs, axis=1).drop('lists', axis=1)
Out[13]: 
           email  0  1
0  [email protected]  1  9
1  [email protected]  6  3

edited May 23, 2017 at 11:53

CommunityBot

11 silver badge

answered Jan 12, 2015 at 5:25

Marius

60.6k16 gold badges115 silver badges108 bronze badges

Sign up to request clarification or add additional context in comments.

1 Comment

Marius Over a year ago

(also sidenote: it's 'column', not 'colon')

Collectives™ on Stack Overflow

Pandas DataFrame: create a column from a list inside a column

1 Answer 1

1 Comment

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

1 Comment

Your Answer

Sign up or log in

Post as a guest

Linked

Related