Pierre GM wrote:

Ryan, Thanks for reporting. An idea would be to force the dtype of the masked column to the largest dtype of the other columns (in your example, that would be int). I'll try to see how easily it can be done early next week. Meanwhile, you can always give an explicit dtype at creation.

Ok, thanks. I've dug a little further, and it seems like the problem is that a column of all missing values ends up as a column of all None's. When you create a (masked) array from a list of None's, you end up with an object array. On one hand I'd love for things to behave differently in this case, but on the other I understand why things work this way. Ryan

On Jan 24, 2009, at 5:58 PM, Ryan May wrote:

...

Pierre,

I've found what I consider to be a bug in the new mafromtxt (though apparently it existed in earlier versions as well). If you have an entire column of data in a file that contains only masked data, and try to get mafromtxt to automatically choose the dtype, the dtype gets selected to be object type. In this case, I'd think the better behavior would be float, but I'm not sure how hard it would be to make this the case. Here's a test case:

import numpy as np from StringIO import StringIO s = StringIO('1 2 3\n4 5 6\n') a = np.mafromtxt(s, missing='2,5', dtype=None) print a.dtype

Ryan

-- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion

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-- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma

Pierre GM wrote:

On Jan 24, 2009, at 6:23 PM, Ryan May wrote:

...

Ok, thanks. I've dug a little further, and it seems like the problem is that a column of all missing values ends up as a column of all None's. When you create a (masked) array from a list of None's, you end up with an object array. On one hand I'd love for things to behave differently in this case, but on the other I understand why things work this way.

Ryan, Mind giving r6434 a try? As usual, don't hesitate to report any problem.

Works great! Thanks for the quick fix. I had racked my brain on how to go about fixing this cleanly, but this is far simpler than what I would have done. It makes sense, since all I really needed for the masked column was something *other* than object. Thanks a lot, Ryan -- Ryan May Graduate Research Assistant School of Meteorology University of Oklahoma