How to convert a list of string to a list of int

Question

I have this list in a list

a = [[\'1\',\'2\',\'3\',\'4\'],[\'1\',\'2\',\'3\',\'4\'],[\'1\',\'2\',\'3\',\'4\']]

but i need it to be ints , im

Answer 1

In [51]: a = [['1','2','3','4'],['1','2','3','4'],['1','2','3','4']]

In [52]: [map(int, l) for l in a]
Out[52]: [[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]]

Answer 2

You can use a nested list comprehension like so:

a = [['1','2','3','4'],['1','2','3','4'],['1','2','3','4']]
b = [ [int(j) for j in i] for i in a]

Answer 3

Here's an idea:

>>> a = [['1','2','3','4'],['1','2','3','4'],['1','2','3','4']]
>>> map(lambda l: map(int, l), a)
[[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]]

Answer 4

An example using nested list comprehension:

In [1]: a = [['1','2','3','4'],['1','2','3','4'],['1','2','3','4']]

In [2]: [[int(s) for s in l] for l in a]
Out[2]: [[1, 2, 3, 4], [1, 2, 3, 4], [1, 2, 3, 4]]