Pandas 将每个单元格都是字符串列表的列转换为整数列表

Question

I have a dataframe with columns that has list of numbers as strings:

C1 C2 l
1   3 ['5','9','1']
7   1 ['7','1','6']

What is the best way to convert it to list of ints?

C1 C2 l
1   3 [5,9,1]
7   1 [7,1,6]

Thanks

Answer 1

Pandas' dataframes are not designed to work with nested structures such as lists. Thus, there is no vectorial method for this task.

You need to loop. The most efficient is to use a list comprehension ( apply would also work but with much less efficiency).

df['l'] = [[int(x) for x in l] for l in df['l']]

NB. There is no check. If you have anything that cannot be converted to integers, this will trigger an error!

Output:

  C1 C2         l
0  1  3 [5, 9, 1]
1  7  1 [7, 1, 6]

Answer 2

You can try

df['l'] = df['l'].apply(lambda lst: list(map(int, lst)))

print(df)

   C1  C2          l
0   1   7  [5, 9, 1]
1   3   1  [7, 1, 6]