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classification
Title: str is number methods don't recognize '.'
Type: behavior Stage: resolved
Components: Interpreter Core Versions: Python 3.4
process
Status: closed Resolution: rejected
Dependencies: Superseder:
Assigned To: Nosy List: brett.cannon, ezio.melotti, ned.deily, ron_adam
Priority: normal Keywords:

Created on 2013-08-14 16:55 by ron_adam, last changed 2022-04-11 14:57 by admin. This issue is now closed.

Messages (6)
msg195186 - (view) Author: Ron Adam (ron_adam) * Date: 2013-08-14 16:55
Shouldn't at least isdecimal return True?

>>> '123.0'.isdecimal()
False
>>> '123.0'.isalnum()
False
>>> '123.0'.isnumeric()
False
>>> '123.0'.isdigit()
False
msg195188 - (view) Author: Ned Deily (ned.deily) * (Python committer) Date: 2013-08-14 17:20
isdecimal() is working as documented, isn't it?  A period character serving as a decimal point is not the same as a decimal character.

"Return true if all characters in the string are decimal characters and there is at least one character, false otherwise. Decimal characters are those from general category β€œNd”. This category includes digit characters, and all characters that can be used to form decimal-radix numbers, e.g. U+0660, ARABIC-INDIC DIGIT ZERO."
msg195197 - (view) Author: Brett Cannon (brett.cannon) * (Python committer) Date: 2013-08-14 18:55
Ned is right, everything is working as documented and intended: as a way to avoid using a regex to test a simple case instead of trying to do anything fancy like identify a number.
msg195203 - (view) Author: Ron Adam (ron_adam) * Date: 2013-08-14 19:15
I get the same resluts if I make the string by str(123.0).  I was thinking it should test True for the isdecimal case for that.

It seems I missunderstood their purpose/use.  This seems like it would be a very common misunderstanding.

It appears, (Because it isn't stated in the doc strings), that they are for testing what specific sub-group of unicode data, the individual character(s) are in.  I think the methods doc strings should say this and be worded so they are more character specific.  

   """ Tests each character, and returns true if
    all of them are in the unicode _______ sub-group. """

As for testing weather or not a string as a whole represents a number value, it seems try/except is still the best way.  :-/
msg195204 - (view) Author: Brett Cannon (brett.cannon) * (Python committer) Date: 2013-08-14 19:21
Feel free to submit an issue suggesting better docstrings as that sounds like it could stand to get some TLC.
msg195323 - (view) Author: Ezio Melotti (ezio.melotti) * (Python committer) Date: 2013-08-16 13:10
> it seems try/except is still the best way.  :-/

Indeed: http://docs.python.org/dev/glossary#term-eafp
History
Date User Action Args
2022-04-11 14:57:49adminsetgithub: 62940
2013-08-16 13:10:03ezio.melottisetnosy: + ezio.melotti

messages: + msg195323
stage: resolved
2013-08-14 19:21:44brett.cannonsetmessages: + msg195204
2013-08-14 19:15:44ron_adamsetmessages: + msg195203
2013-08-14 18:55:05brett.cannonsetstatus: open -> closed

nosy: + brett.cannon
messages: + msg195197

resolution: rejected
2013-08-14 17:20:51ned.deilysetnosy: + ned.deily
messages: + msg195188
2013-08-14 16:55:43ron_adamcreate