[Numpy-discussion] MA bug or feature?
pgmdevlist at mailcan.com
Wed Jun 21 05:12:09 CDT 2006
On Wednesday 21 June 2006 04:46, Michael Sorich wrote:
> When transposing a masked array of dtype '<f8' I noticed that an
> ndarray of dtype '|O4' was returned.
OK, I see where the problem is:
When your fill_value has a type that cannot be converted to the type of your
data, the `filled` method (used internally in many functions, such as
`transpose`) raises a TypeError, which is caught and your array is converted
That's what happen here: your fill_value is a string, your data are integer,
the types don't match, hence the conversion. So, no, I don't think that's a
Why filling when you don't have any masked values, then ? Well, there's a
subtle difference between a boolean mask and a mask of booleans.
When the mask is boolean (mask=nomask=False), there's no masked value, and
`filled` returns the data.
Now, when your mask is an array of boolean (your first case), MA doesn't check
whether mask.any()==False to determine whether there are some missing data or
not, it just processes the whole array of boolean.
I agree that's a bit confusing here, and there might be some room for
improvement (for example, changing the current
`if m is nomask` to `if m is nomask or m.any()==False`, or better, forcing
mask to nomask if mask.any()==False). But I don;t think that qualifies as
when you have an array of numbers, don't try to fill it with characters.
More information about the Numpy-discussion