字符串到int转换的列表

Question

I want to convert a list of python elements from str to int .

My initial list looks like this:

l1 = ['723', '124', '1,211', '356']

The code I tried:

l1 =  list(map(int, l1))

Resulted in an error that tells me:

ValueError: invalid literal for int() with base 10: '1,211'

Alternatively, I tried map ing with float :

l1 =  list(map(float, l1))

but, this also resulted in an error:

ValueError: could not convert string to float: '1,211'

I have tried both int and float in the code using map function. Can anyone correct me on where I'm going wrong.

Answer 1

Mapping either int or float to a value containing ',' will fail as converting str s to floats or ints has the requirement that they represent correctly formed numbers (Python doesn't allow ',' as separators for floats or for thousands, it conflicts with tuples)

If ',' is a thousands separator, use replace(',', '') (as @tobias_k noted) in the comprehension you supply to map and apply the int immediately:

r = list(map(int , (i.replace(',', '') for i in l1)))

to get a wanted result for r of:

[723, 124, 1211, 356]

Answer 2

Do it with a simple list comprehension.

>>> l1 = ['723', '124', '1,211', '356']
>>> [int(i.replace(',','')) for i in l1]
[723, 124, 1211, 356]

Answer 3

This might help:

l1 = ['723', '124', '1,211', '356']
l1 = [int(i.replace(',','')) for i in l1]
for x in l1:
    print("{:,}".format(x))

Output:

723
124
1,211
356