On Sun, Jul 31, 2011 at 10:54 AM, Justin C. Walker <[email protected]> wrote:
>
> On Jul 31, 2011, at 02:29 , tvn wrote:
>
>> The enumerate function in Python has the index type as 'int' instead of say
>> sage's Integer. is there an equivalent of enumerate in Sage that returns
>> Integer type ? Thanks
>
> Try srange and sxrange/xsrange.
Those do something different -- they give a range of values. In
contrast, enumerate takes an iterable x, and returns an iterator over
tuples (i,x[i]) with i a Python int. I think the OP is asking
whether there is something like "senumerate(x)" that would return an
iterator over pairs (i,x[i]), with i Sage integers. I think there is
no such single function. Since it is easy to write such a thing in
2-3 lines of code (see below -- or just throw in a coercion), the only
reason they could be asking is they want maximal speed...? But that
isn't explained in the question. Hmmm. Not sure what to do.
# Here is the 2-liner:
def senumerate(x):
for i, a in enumerate(x): yield Integer(i),a
sage: v = list(senumerate(['a','b','c'])); v
[(0, 'a'), (1, 'b'), (2, 'c')]
sage: type(v[0][0])
<type 'sage.rings.integer.Integer'>
sage: list(enumerate(['a','b','c']))
[(0, 'a'), (1, 'b'), (2, 'c')]
>
> Details with "?"
>
> HTH
>
> Justin
>
> --
> Justin C. Walker
> Curmudgeon at Large
> Director
> Institute for the Enhancement of the Director's Income
> --
> Build a man a fire and he'll be warm
> for a night.
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--
William Stein
Professor of Mathematics
University of Washington
http://wstein.org
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