how to get the ordinal number in list

[Rustom Mody]

On Saturday, August 9, 2014 8:36:28 AM UTC+5:30, Steven D'Aprano wrote:
> luofeiyu wrote:

> >  >>> x=["x1","x3","x7","x5","x3"]
> >  >>> x.index("x3")
> > 1
> > if i want the result of 1 and 4 ?

> def index_all(source, target):
>     results = []
>     for i, obj in enumerate(source):
>         if obj == target:
>             results.append(i)
>     return results

> index_all(x, "x3")
> => returns [1, 3]

Heh!
And the OP asked for a simplification!

>>> def index_all(lst, val): return (i for i,v in enumerate(lst) if v == val)
... 
>>> index_all("abcdeaga", "a")
<generator object <genexpr> at 0x7f21884797d0>
>>> list(index_all("abcdeaga", "a"))
[0, 5, 7]

[To the OP]
Yeah I am in the minority at least out here in considering
comprehensions simpler than loops. Take your pick