[Numpy-discussion] Count the occurrence of a certain integer in a list of integers

Keith Goodman kwgoodman@gmail....
Tue Aug 7 07:24:13 CDT 2007


On 8/7/07, Keith Goodman <kwgoodman@gmail.com> wrote:
> On 8/7/07, Nils Wagner <nwagner@iam.uni-stuttgart.de> wrote:
> > I have a list of integer numbers. The entries can vary between 0 and 19.
> > How can I count the occurrence of any number. Consider
> >
> >  >>> data
> > [9, 6, 9, 6, 7, 9, 9, 10, 7, 9, 9, 6, 7, 9, 8, 8, 11, 9, 6, 7, 10, 9, 7, 9, 7, 8, 9, 8, 7, 9]
> >
> >
> > Is there a better way than using, e.g.
> >
> > >>> shape(where(array(data)==10))[1]
> > 2
> >
> >
> > to compute the occurrence of 10 in the list which is 2 in this case ?
>
> Would list comprehension work?
>
> len([z for z in data if z == 10])

Or is this faster?

(array(x)==10).sum()


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