[Numpy-discussion] numarray incompatibility: searchsorted
Todd Miller
jmiller at stsci.edu
Fri Sep 26 11:08:01 CDT 2003
I logged this on Source Forge. Thanks for the comments.
Todd
On Fri, 2003-09-26 at 13:06, Tim Hochberg wrote:
>
> There are some compatibility and doc issues and perhaps a bug in
> numarray.searchsorted. The compatibility issue is that
> Numeric.searchsorted(a, v) accepts either a sequence or scalar value for
> v. Numarray.searchsorted accepts only sequence values.
>
> Second, the doc issue. The docstring for numarray.searchsorted states::
>
> searchsorted(bins, values)
> searchsort(bins, values) returns the array of greatest indices 'i'
> such that each values[i] <= bins[i].
>
> I assume that should really read something more like::
>
> searchsorted(bins, values)
> searchsort(bins, values) returns the array A[j] of greatest indices 'i'
> such that each values[j] <= bins[i].
>
> Third, the possible bug:
>
> # na = numarray, np = NumPy
> >>> na.searchsorted([1,2,3,4], [2.5, 3.5])
> array([1, 2])
> >>> np.searchsorted([1,2,3,4], [2.5, 3.5])
> array([2, 3])
>
> Hmmm. It appears that numarray result does match the numarray docs, (at
> least as I read them), but I like the Numeric behaviour better. The
> Numeric behaviour also matches the behaviour of the bisect module, which
> is described as::
>
> bisect = bisect_right(a, x, lo=0, hi=None)
> Return the index where to insert item x in list a, assuming a is
> sorted.
>
> The return value i is such that all e in a[:i] have e <= x, and
> all e in
> a[i:] have e > x. So if x already appears in the list, i points
> just
> beyond the rightmost x already there.
>
> Optional args lo (default 0) and hi (default len(a)) bound the
> slice of a to be searched.
>
> I'd recomend matching the behaviour of the two existing modules (bisect
> and Numeric).
>
> -tim
>
>
>
>
>
>
>
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--
Todd Miller jmiller at stsci.edu
STSCI / ESS / SSB
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