[Numpy-discussion] Indexing issue with ndarrays
jfoxrabinovitz at gmail.com
Thu Aug 25 10:36:50 EDT 2016
This issue recently came up on Stack Overflow:
The poster attempted to index an ndarray with a pandas boolean Series
object (all False), but the result was as if he had indexed with an array
of integer zeros.
Can someone explain this behavior? I can see two obvious possibilities:
1. ndarray checks if the input to __getitem__ is of exactly the right
type, not using instanceof.
2. pandas actually uses a wider datatype than boolean internally, so
indexing with the series is in fact indexing with an integer array.
In my attempt to reproduce the poster's results, I got the following
FutureWarning: in the future, boolean array-likes will be handled as a
boolean array index
This indicates that the issue is probably #1 and that a fix is already on
the way. Please correct me if I am wrong. Also, where does the code for
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