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Tue Sep 6 09:34:02 EDT 2005 · http://mail.python.org/pipermail/python-list/2005-September/299759.html

Ron Adam wrote:

>> This should never fail with an assertion error.  You will note that it
>> shows that, for non-negative start and end values, slicing behavior is
>> _exactly_ like extended range behavior.

> Yes, and it passes for negative start and end values as well.

Umm, no:

.>> for stride in [-3, -2, -1, 1, 2, 3]:
...     for start in range(-1,len(L)):
...         for end in range(-1,len(L)):
...             P = L[start:end:stride]
...             Q = [L[i] for i in range(start, end, stride)]
...             assert P==Q, [start, end, stride, P, Q]
...
Traceback (most recent call last):
  File "<stdin>", line 6, in ?
AssertionError: [-1, 0, -3, [9, 6, 3], []]

> Thanks again, this pretty much explains why slices opperate the
> way they do.  And it explains why the edge case's happen as well I think.

You're welcome.

Regards,
Pat

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Showing content from http://mail.python.org/pipermail/python-list/2005-September/299759.html below:

Possible improvement to slice opperations.