Filter a list in python get integers
I have a list:
['Jack', 18, 'IM-101', 99.9]
How do I filter it to get only the integers from it??
I tried
map(int, x)
but it gives error.
开发者_如何转开发ValueError: invalid literal for int()
with base 10: 'Jack'
>>> x = ['Jack', 18, 'IM-101', 99.9]
>>> [e for e in x if isinstance(e, int)]
[18]
In case the list contains integers that are formatted as str
, the isinstance()
solutions would not work.
['Jack', '18', 'IM-101', '99.9']
I figured out the following alternative solution for that case:
list_of_numbers = []
for el in your_list:
try:
list_of_numbers.append(int(el))
except ValueError:
pass
You can find more details about this solution in this post, containing a similar question.
Use filter
:
filter(lambda e: isinstance(e, int), x)
Use list comprehension
>>> t = ['Jack', 18, 'IM-101', 99.9]
>>> [x for x in t if type(x) == type(1)]
[18]
>>>
map(int, x) throws an error
map function applies int(t) on every element of x.
This throws an error because int('Jack') will throw an error.
[Edit:]
Also isinstance is purer way of checking that it is of type integer, as sukhbir says.
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