Bugs item #1602378, was opened at 2006-11-24 12:07
Message generated for change (Settings changed) made by rhettinger
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1602378&group_id=5470
Please note that this message will contain a full copy of the comment thread,
including the initial issue submission, for this request,
not just the latest update.
Category: Documentation
Group: Python 2.5
>Status: Closed
>Resolution: Fixed
Priority: 4
Private: No
Submitted By: Daniel Eloff (eloff)
Assigned to: Raymond Hettinger (rhettinger)
Summary: Incorrect docs for bisect_left
Initial Comment:
Quote:
Return the index where to insert item x in list a, assuming a is sorted.
The return value i is such that all e in a[:i] have e < x, and all e in a[i:]
have e >= x. So if x already appears in the list, i points just before the
leftmost x already there.
The last sentence is incorrect, and it contradicts what comes earlier. Not
knowing which is correct, I had to test it in the shell.
>>> from bisect import *
>>> l = [1,2,3,3,3,4,5]
>>> bisect_left(l,3)
2
>>> l[2:]
[3, 3, 3, 4, 5]
It should be changed to read "i points at the leftmost x already there"
-Dan
----------------------------------------------------------------------
>Comment By: Raymond Hettinger (rhettinger)
Date: 2007-04-02 19:02
Message:
Logged In: YES
user_id=80475
Originator: NO
Fixed. See versions 54665 and 64666.
----------------------------------------------------------------------
Comment By: Daniel Eloff (eloff)
Date: 2006-12-03 17:39
Message:
Logged In: YES
user_id=730918
Originator: YES
That makes more sense, but if that's explained anywhere it was hidden away
where I've never discovered it. I would be in favor of you're suggested fix
to the line in question.
-Dan
----------------------------------------------------------------------
Comment By: Tim Peters (tim_one)
Date: 2006-11-24 14:16
Message:
Logged In: YES
user_id=31435
Originator: NO
The docs are written from the POV that indices in Python point /between/
array elements, which is the easiest way to understand slices, and that
there are n+1 non-negative indices that "make obvious sense" in slices of a
sequence with n elements: index 0 points "just before" element a[0], and
index n "just after" element a[n-1], while for 0 < i < n-1, index i points
"just before" element [i] /and/ "just after" element a[i-1].
This is also the sanest way to understand the return value of the bisect
functions, which again can return n+1 values given a sequence with n
elements.
That said, I agree the docs are cryptic if you don't understand that
first. I'm not sure this is the best place to explain it. The specific
line in question could be "repaired" by saying a[i] is the leftmost x
already there, identifying one of the n elements instead of one of the n+1
sequence positions.
----------------------------------------------------------------------
You can respond by visiting:
https://sourceforge.net/tracker/?func=detail&atid=105470&aid=1602378&group_id=5470
_______________________________________________
Python-bugs-list mailing list
Unsubscribe:
http://mail.python.org/mailman/options/python-bugs-list/archive%40mail-archive.com
