learning to use iterators

[Rustom Mody]

On Wednesday, December 24, 2014 8:42:32 PM UTC+5:30, Vito De Tullio wrote:
> Seb wrote:
> 
> >>>> def n_grams(a, n):
> > ...     z = (islice(a, i, None) for i in range(n))
> > ...     return zip(*z)
> > ...
> > 
> > I'm impressed at how succinctly this islice helps to build a list of
> > tuples with indices for all the required windows.
> 
> If you want it succinctly, there is this variation on the theme:
> 
> n_grams = lambda a, n: zip(*(a[i:] for i in range(n)))

+3 but -1
+1 for using an inlining the z
+1 for showing that the * can take any expression [I did not know that]
+1 for the slice in succinct form

-1 for the lambda -- quite unnecessary and a red-herring

If squeezing out the last char is the idea

n_grams = lambda a, n: zip(*(a[i:] for i in range(n)))

is same as

def n_grams(a,n):return zip(*(a[i:]for i in range(n)))