On 2023-03-06 00:28, dn via Python-list wrote:
On 06/03/2023 11.59, aapost wrote:
On 3/5/23 17:43, Stefan Ram wrote:
The following behaviour of Python strikes me as being a bit
"irregular". A user tries to chop of sections from a string,
but does not use "split" because the separator might become
more complicated so that a regular expression will be required
to find it. But for now, let's use a simple "find":
|>>> s = 'alpha.beta.gamma'
|>>> s[ 0: s.find( '.', 0 )]
|'alpha'
|>>> s[ 6: s.find( '.', 6 )]
|'beta'
|>>> s[ 11: s.find( '.', 11 )]
|'gamm'
|>>>
. The user always inserted the position of the previous find plus
one to start the next "find", so he uses "0", "6", and "11".
But the "a" is missing from the final "gamma"!
And it seems that there is no numerical value at all that
one can use for "n" in "string[ 0: n ]" to get the whole
string, isn't it?
I would agree with 1st part of the comment.
Just noting that string[11:], string[11:None], as well as string[11:16]
work ... as well as string[11:324242]... lol..
To expand on the above, answering the OP's second question: the numeric
value is len( s ).
If the repetitive process is required, try a loop like:
>>> start_index = 11 #to cure the issue-raised
>>> try:
... s[ start_index:s.index( '.', start_index ) ]
... except ValueError:
... s[ start_index:len( s ) ]
...
'gamma'
Somewhat off-topic, but...
When there was a discussion about a None-coalescing operator, I thought
that it would've been nice if .find and .rfind returned None instead of -1.
There have been times when I've wanted to find the next space (or
whatever) and have it return the length of the string if absent. That
could've been accomplished with:
s.find(' ', pos) ?? len(s)
Other times I've wanted it to return -1. That could've been accomplished
with:
s.find(' ', pos) ?? -1
(There's a place in the re module where .rfind returning -1 is just the
right value.)
In this instance, slicing with None as the end is just what's wanted.
Ah, well...
--
https://mail.python.org/mailman/listinfo/python-list
