[Numpy-discussion] setmember1d memory leak?
Charles R Harris
charlesr.harris at gmail.com
Wed Jan 24 11:30:33 EST 2007
On 1/24/07, Robert Cimrman <cimrman3 at ntc.zcu.cz> wrote:
> Robert Kern wrote:
> > Robert Cimrman wrote:
> >> Or you could just call unique1d prior to your call to setmember1d - it
> >> was meant to be used that way... you would not loose much speed that
> >> way, IMHO.
> > But that doesn't do what they want. They want a function that gives the
> > against their original array of the elements that are in the other
> array. The
> > result of
> > setmember1d(unique1d(ar1), unique1d(ar2))
> > is a mask against
> > unique1d(ar1)
> > not
> > ar1
> > as they want.
> I see. I was thinking in terms of 'set member' - in set one assumes
> unique elements. A good name for this kind of function would be
> Naive pseudo-implementation:
> import numpy as nm
> def arraymember1d( ar1, ar2 ):
> ar = ar2.copy().sort()
> indx = findsorted( ar2, ar1 )
> flag = nm.zeros( ar1.shape, dtype = nm.bool )
> flag[indx] = True
> return flag
> Note that nm.searchsorted cannot be used here - a new function
> ('findsorted'?) would be needed.
Maybe something like
countelements(ar1, ar2) :
a = sort(ar2)
il = a.searchsorted(ar1, side='left')
ir = a.searchsorted(ar1, side='right')
return ir - il
which returns an array containing the number of times the corresponding
element of ar1 is contained in ar2.
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