How can I check if a string contains ANY letters from the alphabet?

Question

What is best pure Python implementation to check if a string contains ANY letters from the alphabet?

string_1 = \"(555).555-5555\"
string_2 = \"(555) 555 - 5         


        

Answer 1

How about:

>>> string_1 = "(555).555-5555"
>>> string_2 = "(555) 555 - 5555 ext. 5555"
>>> any(c.isalpha() for c in string_1)
False
>>> any(c.isalpha() for c in string_2)
True

Answer 2

Regex should be a fast approach:

re.search('[a-zA-Z]', the_string)

Answer 3

I liked the answer provided by @jean-françois-fabre, but it is incomplete.
His approach will work, but only if the text contains purely lower- or uppercase letters:

>>> text = "(555).555-5555 extA. 5555"
>>> text.islower()
False
>>> text.isupper()
False

The better approach is to first upper- or lowercase your string and then check.

>>> string1 = "(555).555-5555 extA. 5555"
>>> string2 = '555 (234) - 123.32   21'

>>> string1.upper().isupper()
True
>>> string2.upper().isupper()
False

Answer 4

You can also do this in addition

import re
string='24234ww'
val = re.search('[a-zA-Z]+',string) 
val[0].isalpha() # returns True if the variable is an alphabet
print(val[0]) # this will print the first instance of the matching value

Also note that if variable val returns None. That means the search did not find a match

Answer 5

You can use islower() on your string to see if it contains some lowercase letters (amongst other characters). or it with isupper() to also check if contains some uppercase letters:

below: letters in the string: test yields true

>>> z = "(555) 555 - 5555 ext. 5555"
>>> z.isupper() or z.islower()
True

below: no letters in the string: test yields false.

>>> z= "(555).555-5555"
>>> z.isupper() or z.islower()
False
>>> 

Not to be mixed up with isalpha() which returns True only if all characters are letters, which isn't what you want.

Note that Barm's answer completes mine nicely, since mine doesn't handle the mixed case well.

Answer 6

You can use regular expression like this:

import re

print re.search('[a-zA-Z]+',string)