如何在python中检查混合类型列表中是否有字符串项目

Question

Say I have a list l1 = ['s',1,2] and l2 = [1,2,3] . Obviously l1 has an item of string type and l2 doesn't.

But when a list gets super large and I do not know the items in a list, how do I know if this list contains an item of string type.

Answer 1

if any(isinstance(x, str) for x in your_list):
    print("the list contains a string")

Answer 2

You can use a loop and check if, at each index of your array, the value is corresponding to a number. Use ascii code ( code 48 to 57 for 0 to 9) If the ascii code of your value is between 48 and 57, you know it's a number. If not, you know it's not a number.

Hope this helps

Answer 3

I just saw this post : What's the canonical way to check for type in python?

quote : "Since Python encourages Duck Typing, you should just try to use the object's methods the way you want to use them. So if your function is looking for a writable file object, don't check that it's a subclass of file, just try to use its .write() method!" (This answer were quite suprising to me)

The way i understood that is that you have to act like if all your items in your list were like you want (we don't know yet what do you want to do with your lists).

Answer 4

您可以尝试以下方法：

if any(type(each_item) is str for each_item in l1): # Do something

Answer 5

The solution using isinstance function:

def hasString(l):
    for item in l:
        if isinstance(item, str):
            return True
    return False

l1 = [1, 2, 3]
l2 = ['s', 2, 3]

print(hasString(l1))  # False
print(hasString(l2))  # True