如何识别 Python 中是否至少有一个大写字母？

Question

First of all, I'm quite new with Python.

As the title says, I want to identify if a string contains, at least, one capital letter. If not, I will raise an error saying something like there is no capital letter detected . I have found that the any() function would help me with that, but when I put it on the function it returns the error 'bool' object is not iterable .

Here's what I got:

def identify_capital(x):
    if any(x.isupper()) == True:
        return True
    else:
        raise ValueError("No capital letter detected")

Also, I've tried it with a for loop but it returns the following error 'int' object is not subscriptable . Here's the code:

def identify_capital(x):
    for letter in range(len(x)):
        if letter[i] in x.isupper():
            return True
        else:
            raise ValueError("No capital letter detected")

Thanks for your help and, if more information is needed, let me know.

Answer 1

You can use just map with a isupper function

For example:

s = "abcAs"
contains_upper_case = any(map(str.isupper, s))
print(contains_upper_case)

Answer 2

The any function should accept an iterable of bool values, not a single bool value as returned by x.isupper() . Iterate over the characters in the string:

>>> test1 = 'foo bar'
>>> test2 = 'foo Bar'
>>> any(c.isupper() for c in test1)
False
>>> any(c.isupper() for c in test2)
True

An alternative way using the regex character class [AZ] to match an uppercase letter:

>>> import re
>>> re.search('[A-Z]', test1)
>>> re.search('[A-Z]', test2)
<_sre.SRE_Match object; span=(4, 5), match='B'>

The re.search function returns a truthy Match object or a falsey None , so you can use it in an if statement like so:

if re.search('[A-Z]', x):
    ...