如何将列表的所有值转换为整数？

Question

Hitting a huge roadblock because I can't seem to convert this list into integers.

grades = [
    # First line is the descriptive header. Subsequent lines hold data
    ['Student', 'Exam 1', 'Exam 2', 'Exam 3'],
    ['Thorny', '100', '90', '80'],
    ['Mac', '88', '99', '111'],
    ['Farva', '45', '56', '67'],
    ['Rabbit', '59', '61', '67'],
    ['Ursula', '73', '79', '83'],
    ['Foster', '89', '97', '101']
]

values = [data[1:] for data in grades[1:]]

When I try to convert values to be all integers, I keep getting errors I have tried...

val=int(x) for x in values

and...

int_list = map(int, values)
print(list(int_list))

Any help would be appreciated!

Answer 1

values is a list of lists:

>>> values
[['100', '90', '80'], ['88', '99', '111'], ['45', '56', '67'], ['59', '61', '67'], ['73', '79', '83'], ['89', '97', '101']]

so you'll need to iterate through that:

>>> [list(map(int, value)) for value in values]
[[100, 90, 80], [88, 99, 111], [45, 56, 67], [59, 61, 67], [73, 79, 83], [89, 97, 101]]

Answer 2

When getting the values , you can directly cast them to int , eg,

values = [data[:1] + [int(v) for v in data[1:]] for data in grades[1:]]

or using destructuring and the * -operator:

values = [[name, *map(int, data)] for name, *data in grades[1:]]