Why "ǃ".isalpha() is True but "!".isalpha() is False?

Question

I have just found this strange behaviour parsing data from IANA.

"ǃ".isalpha() # returns True
"!".isalpha() # returns False

Apparently, the two exclamation marks are different:

In [62]: hex(ord("ǃ"))                                                          
Out[62]: '0x1c3'

In [63]: hex(ord("!"))                                                          
Out[63]: '0x21'

Just wondering is there a way to prevent this to happen? What is the origin of this behaviour?

@jonrsharpe yes I undestand this. But I think this is quite a strange behaviour... You would not expect ! to be an alpha — G M, Jun 24 '21 at 08:41
```>>> import unicodedata >>> unicodedata.category("ǃ") # 'Lo' >>> unicodedata.category("!") # 'Po'``` — Azat Ibrakov, Jun 24 '21 at 08:41
so all questions should go to the organisation behind Unicode I guess — Azat Ibrakov, Jun 24 '21 at 08:43
Have a look as https://www.compart.com/en/unicode/U+01C3 . You see it is categorized as "Other Letter". — Klaus D., Jun 24 '21 at 08:44
`ǃ` is part of an alphabet, not an exclamation mark. See https://en.wikipedia.org/wiki/Retroflex_click — blhsing, Jun 24 '21 at 08:44
@blhsing thanks I think this is the answer to my question please formalize it in an answer — G M, Jun 24 '21 at 08:59
You should go find some recordings of how this is pronounced – it's quite amazing. — lenz, Jun 24 '21 at 10:11

score 2 · Accepted Answer · answered Jun 24 '21 at 10:01

Check characters in Unicode Database. The exclamation-like ǃ (\u1c3) is a letter:

import unicodedata
for c in "!ǃ":
    print(c,'{:04x}'.format(ord(c)),unicodedata.category(c), unicodedata.name(c))

! 0021 Po EXCLAMATION MARK
ǃ 01c3 Lo LATIN LETTER RETROFLEX CLICK

ThePyGuy · Answer 2 · 2021-06-24T08:50:15.523

From docs:

str.isalpha()

Return True if all characters in the string are alphabetic and there is at least one character, False otherwise. Alphabetic characters are those characters defined in the Unicode character database as “Letter”, i.e., those with general category property being one of “Lm”, “Lt”, “Lu”, “Ll”, or “Lo”. Note that this is different from the “Alphabetic” property defined in the Unicode Standard.

It means the utf character you are using is defined as letter in the utf database.

>>> ord("ǃ")
   451

Looking at Wikipedia List of UTF characters, the character ǃ falls under the Latin Extended B, and that's why isalpha returns True

Why "ǃ".isalpha() is True but "!".isalpha() is False?

2 Answers2