As a follow-up to Robert's answer: >>> r[r.field1 == 1].field2 = 1 doesn't work, but
>>>r.field2[r.field1==1] = 1 does. > So far, so good. > Now I want to change the value of field2 for those same elements: > > In [128]: r[where(r.field1 == 1.)].field2 = 1 > > Ok, so now the values of field 2 have been changed, for those elements > right? > > In [129]: r.field2 > > Out[129]: array([ 0., 0., 0., 0., 0.]) > > Wait. What? > That can't be right. Let's check again: > > In [130]: print r[where(r.field1 == 1.)].field2 > [ 0. 0.] > > Ok, so it appears that I can *access* fields in this array with an > array of indices, but I can't assign new values to fields so > accessed. However, I *can* change the values if I use a scalar > index. This is different from the behavior of ordinary arrays, for > which I can reassign elements' values either way. > > Moreover, when I try to reassign record array fields by indexing with > an array of indices, it would appear that nothing at all happens. > This syntax is equivalent to the pass command. > > So, my question is this: is there some reason for this behavior in > record arrays, which is unexpectedly different from the behavior of > normal arrays, and rather confusing. If so, why does the attempt to > assign values to fields of an indexed subarray not raise some kind of > error, rather than doing nothing? I think it's unlikely that I've > actually found a bug in numpy, but this behavior does not make sense > to me. > > > Thanks for any insights, > > Brian > > > > _______________________________________________ > Numpy-discussion mailing list > Numpy-discussion@scipy.org > http://projects.scipy.org/mailman/listinfo/numpy-discussion _______________________________________________ Numpy-discussion mailing list Numpy-discussion@scipy.org http://projects.scipy.org/mailman/listinfo/numpy-discussion
