[Numpy-discussion] extract elements of an array that are contained in another array?
Thu Jun 4 15:38:40 CDT 2009
> intersect1d should throw a domain error if you give it arrays with
> non-unique elements, which is not done for speed reasons
It seems to me that this is the basic source of the problem. Perhaps
this can be addressed? I realize maintaining compatibility with the
current behaviour is necessary, so how about a multistage deprecation:
1. add a keyword argument to intersect1d "assume_unique"; if it is not
present, check for uniqueness and emit a warning if not unique
2. change the warning to an exception
3. change the meaning of the function to that of intersect1d_nu if the
keyword argument is not present
One could do something similar with setmember1d.
This would remove the pitfall of the 1d assumption and the wart of the
_nu names without hampering performance for people who know they have
unique arrays and are in a hurry.
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