Remove zeros from Dataframe of lists

Question

I have such a DataFrame:

index	B
0	[0,1,2,0,4]
1	[1,0,2,0,0,1,7]

I want to count the non zero values of each list for each row. Result:

index	B
0	3
1	4

Answer 1

def count_nonzero_elements_of_list(x):
    return len([x if x != 0])

df['B'].apply(count_nonzero_elements_of_list)

Answer 2

By using numpy's count_nonzero method:

import numpy as np

df['B'] = [np.count_nonzero(x) for x in df['B'].tolist()]

Answer 3

using numpy :

df['C'] = df.B.apply(np.count_nonzero)

output:

>>>
                       B  C
0        [0, 1, 2, 0, 4]  3
1  [1, 0, 2, 0, 0, 1, 7]  4