Path: csiph.com!fu-berlin.de!uni-berlin.de!not-for-mail
From: Stephen Hansen <me@ixokai.io>
Newsgroups: comp.lang.python
Subject: Re: Not x.islower() has different output than x.isupper() in list output...
Date: Fri, 29 Apr 2016 23:43:24 -0700
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Xref: csiph.com comp.lang.python:107909

On Fri, Apr 29, 2016, at 06:55 PM, Christopher Reimer wrote:
> On 4/29/2016 6:29 PM, Stephen Hansen wrote:
> > If isupper/islower were perfect opposites of each-other, there'd be no 
> > need for both. But since characters can be upper, lower, or *neither*, 
> > you run into this situation.
> 
> Based upon the official documentation, I was expecting perfect opposites.
> 
> str.islower(): "Return true if all cased characters [4] in the string 
> are lowercase and there is at least one cased character, false
> otherwise."

The thing is, your use of filter is passing a string of 1 character long
to your function, and so when it comes up against a string " ", there
are no cased characters. Therefore, false.

The documentation holds true. 

Your use of filter is breaking "Whiskey Tango Foxtrot" into ["W", "h",
"i", ... "o" t"] and calling not x.islower() vs x.isupper() on each.

When it comes up against " ", it doesn't pass the documented definition
of what islower defines. 

The official documentation is accurate.

-- 
Stephen Hansen
  m e @ i x o k a i  . i o