How to check if a list contains a string

Question

I need to iterate through a list and check if the value is a string or an int. Is there any easy way to do this in python?

For example:

[1,2,3] would be true.

["a",2,3] would be false.

Answer 1

You could do this using all , which would short circuit once a false condition is met.

>>> my_list = [1, 2, 3]
>>> all(type(d) == int for d in my_list)
True

>>> my_list = ['1', 2, 3]
>>> all(type(d) == int for d in my_list)
False

isinstance could be used when calling all as well:

>>> my_list = [1, 2, 3]
>>> all(isinstance(d, int) for d in my_list)
True

>>> my_list = ['1', 2, 3]
>>> all(isinstance(d, int) for d in my_list)
False

Answer 2

You can use a combination of any() and isinstance() :

In [1]: def contains_string(l):
    ...:     return any(isinstance(item, basestring) for item in l)
    ...: 

In [2]: contains_string([1,2,3])
Out[2]: False

In [3]: contains_string(['a',2,3])
Out[3]: True

basestring handles both "unicode" and "str" string types:

• What is the difference between isinstance('aaa', basestring) and isinstance('aaa', str)?

Note that any() would short-circuit as well once it knows the result, see more about that here:

• How do Python's any and all functions work?

Answer 3

Assuming you meant that you need to check through all the values of the list and that only if they were all integers the function would return True, this is how I'd do it:

def test(list):
    result=True
    for elem in list:
        if type(elem)!=int:
            result=False
    return result