Iterating through a list of string lists?

Question

I'm new to Python, coming from C; this is my first post, I looked all over for help on how to solve my problem but I cannot find it anywhere unfortunately.

I have a list of lists, and within the lists are strings of numbers(sorting dates):

    d = [['2012', '11', '14'], ['2012', '11', '13'], ['2012', '11', '12']]

I am trying to convert these string numbers into integers but i'm not sure how to do it using the way i had used for a normal string list, which was

    int_list = [int(x) for x in str_list]

How do i iterate through my list of lists and convert the string numbers into integers so that my list looks like this instead

    d = [[2012, 11, 14], [2012, 11, 13], [2012, 11, 12]]

Sorry if this question has been asked before but I could really use some help! Thanks in advance!

Answer 1

You can use map with list comprehension.

d=[map(int,i) for i in d]

For python 3.x, use:

d=[list(map(int,i)) for i in d]

Answer 2

just use list comprehension:

>>> d = [['2012', '11', '14'], ['2012', '11', '13'], ['2012', '11', '12']]
>>> i = [[int(x) for x in l] for l in d]
>>> i
[[2012, 11, 14], [2012, 11, 13], [2012, 11, 12]]

i think your problem was that it is a nested list so iterating (int(x)) through d is trying to convert lists into ints

Answer 3

嵌套列表理解可以很好地工作：

d = [[int(x) for x in sublist] for sublist in d]