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开发者_如何学运维 How to convert strings into integers in python?

I need to change a list of strings into a list of integers how do i do this

i.e

('1', '1', '1', '1', '2') into (1,1,1,1,2).

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Use list comprehensions:

strtuple = ('1', '1', '1', '1', '2')
intlist = [int(s) for s in strtuple]

Stuff for completeness:

As your “list” is in truth a tuple, i.e. a immutable list, you would have to use a generator expression together with a tuple constructor to get another tuple back:

inttuple = tuple(int(s) for s in strtuple)

The “generator expression” i talk about looks like this when not wrapped in a constructor call, and returns a generator this way.

intgenerator = (int(s) for s in strtuple)

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map(int, ls)

Where ls is your list of strings.

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Use the map function.

vals = ('1', '1', '1', '1', '2')
result = tuple(map(int, vals))
print result

Output:

(1, 1, 1, 1, 2)

A performance comparison with the list comprehension:

from timeit import timeit
print timeit("map(int, vals)", "vals = '1', '2', '3', '4'")
print timeit("[int(s) for s in strlist]", "strlist = ('1', '1', '1', '1', '2')")

Output:

3.08675879197
4.08549801721

And with longer lists:

print timeit("map(int, vals)", "vals = tuple(map(str, range(10000)))", number = 1000)
print timeit("[int(s) for s in strlist]", "strlist = tuple(map(str, range(10000)))", number = 1000)

Output:

6.2849350965
7.36635214811

It appears that, (on my machine) in this case, the map approach is faster than the list comprehension.

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You could use list comprehension which would look roughly like:

newList = [int(x) for x in oldList]