![](https://secure.gravatar.com/avatar/226e40fdc55d4597a46279296a616384.jpg?s=120&d=mm&r=g)
I feel kinda stupid as I think this must be easier than I am making it. Below my question you will see an answer I got to a question that I thought I would be able to complete the last steps my self I was wrong :) So if I have an array Y = np.rec.array([(1.0, 0.0, 3.0, 3.5), (0.0, 0.0, 6.0, 6.5), (1.0, 1.0, 9.0, 9.5)], dtype=[('var1', '<f8'), ('var2', '<f8'), ('var3', '<f8'), ('var4', '<f8')]) do this works like I would expect Y[['var3','var4']][Y['var1']==1]
array([(3.0, 3.5), (9.0, 9.5)],
dtype=[('var3', '<f8'), ('var4', '<f8')]) But I would like to do this,
Y[['var3','var4']][Y['var1']==0 and Y['var2']==0]
Traceback (most recent call last): File "<string>", line 1, in <fragment> ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() I tried some any() and all() combination but nothing worked. What s the right way to go about this? Thanks Vincent This answer was received on the mail list from Skipper Seabold If you have a rec array Y = np.rec.array([(1.0, 2.0, 3.0), (4.0, 5.0, 6.0), (7.0, 8.0, 9.0)], dtype=[('var1', ''var2','var3']) You can access the rows like, Y[['var1','var2','var3']] Note the list within []. If you want a "normal" array, I like this way that Pierre recently pointed out. 3 is the number of columns, and it fills in the number of rows. Y[['var1','var2','var3']].view((float,3)) note the tuple for the view, if they're all floats. Taking a view might not work if var# have different types, like ints and floats. If you want the mean of the rows (mean over the columns axis = 1) Y[['var1','var2','var3']].view((float,3)).mean(1) Some shortcuts. Y[list(Y.dtype.names)].view((float,len(Y.dtype))).mean(1) Also, for now, the columns will given back to you in the order they're in in the array no matter which way you ask for them. A patch has been submitted for returning the order you ask that I hope gets picked up... *Vincent Davis 720-301-3003 * vincent@vincentdavis.net my blog <http://vincentdavis.net> | LinkedIn<http://www.linkedin.com/in/vincentdavis>