nested loops in Python
Igor Kozin
ink.icr at gmail.com
Fri Sep 9 06:48:15 EDT 2016
I think you are right, it's the assignment itself which is slow.
Merged loop is only a tad quicker.
On Thursday, September 8, 2016 at 6:04:41 PM UTC+1, Christian Gollwitzer wrote:
> > Why nested loops are so slow in Python? Is it because new contexts are created?
> > For more details, see
> > http://stackoverflow.com/questions/26611043/numpy-vs-cython-nested-loop-so-slow
> > http://stackoverflow.com/questions/39371021/efficient-loop-over-numpy-array
>
> The answers are right there, too - what are you mising? CPython is an
> interpreter. For every seemingly simple operation like a[i]=j, a
> function pointer is called, the variables contain polymorphic types
> which are morphed, etc. The same thing in compiled code is a single
> machine instruction. Speed differences of ~100x are normal between
> compiled and interpreted code over all dynamic languages.
>
> Christian
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