Assuming this is a string column you can use the str.split
method:
In [11]: df['time taken'].str.split(':')
Out[11]:
0 [02, 08, 00]
1 [02, 05, 00]
2 [02, 55, 00]
3 [03, 42, 00]
4 [01, 12, 00]
5 [01, 46, 00]
6 [03, 22, 00]
7 [03, 36, 00]
Name: time taken, dtype: object
And then use apply
:
In [12]: df['time taken'].str.split(':').apply(lambda x: int(x[0]) * 60 + int(x[1]))
Out[12]:
0 128
1 125
2 175
3 222
4 72
5 106
6 202
7 216
Name: time taken, dtype: int64