Convert Pandas df column list of strings to ints

Question

I have a df like this"

col1
['525', '2830', '43', '567']    
['432', '324', '3993', '5675']  
['234', '2830', '342312', '4410']

df.applymap(type) shows all rows in this column are <class 'str'>:

I'm trying to convert the elements in this df.col to integers and sum them in a new column. I've tried like a billion things but have been unsuccessful.

#attempts
#converted to list
map(int, list()) 
map(int, list().split()) 

#geeks for geeks suggestions:
for i in range(0, len(list)): 
    list[i] = int(list[i]) 

test_list = [int(i) for i in test_list]

I just get this error constantly:

ValueError: invalid literal for int() with base 10: '[525 2830 3993 4410]'

Any ideas?

Andrej Kesely · Accepted Answer · 2020-09-08 21:37:17Z

1

df['sum'] = df['col1'].apply(lambda x: sum(int(v) for v in x))
print(df)

Prints:

                        col1     sum
0       [525, 2830, 43, 567]    3965
1     [432, 324, 3993, 5675]   10424
2  [234, 2830, 342312, 4410]  349786

EDIT:

import ast

df['sum'] = df['col1'].apply(lambda x: sum(int(v) for v in ast.literal_eval(x)))
print(df)

edited Sep 8, 2020 at 21:37

answered Sep 8, 2020 at 21:18

Andrej Kesely

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4 Comments

max Over a year ago

I'm getting this error: ValueError: invalid literal for int() with base 10: '['??

Andrej Kesely Over a year ago

@max See my edit. It seems that you store strings instead of lists in col1.

max Over a year ago

one more question - what if i wanted to add a column that counts the number of items in each of these lists? 4, 4, 4 for the example above

Andrej Kesely Over a year ago

@max You can do df["len"] = df["col1"].apply(lambda x: len(ast.literal_eval(x)))

Andy L. · Accepted Answer · 2020-09-08 21:23:47Z

1

Try this

import ast
df.col1.map(lambda x: sum(map(int, ast.literal_eval(x))))

Out[789]:
0      3965
1     10424
2    349786
Name: col1, dtype: int64

answered Sep 8, 2020 at 21:23

Andy L.

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