[SciPy-User] accessing a set of columns from a recarray
Mon Mar 22 00:09:22 CDT 2010
I posted the question on ask.scipy.org, I just posted your response, If you
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On Sun, Mar 21, 2010 at 8:33 PM, Skipper Seabold <email@example.com>wrote:
> On Sun, Mar 21, 2010 at 10:20 PM, Vincent Davis
> <firstname.lastname@example.org> wrote:
> > To many distractions let me try to write that a little better.
> > I have a record array and a list of columns for which I would like to get
> the row means. My current solution is to iterate though the list of column
> names and make a new "normal" array. then calculate the row means. I would
> like to do something like np.mean(A['x','y','z']) where x,y,z are the tiles
> of the columns
> 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', '<f8'), ('var2', '<f8'), ('var3', '<f8')])
> You can access the rows like,
> 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.
> 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)
> Some shortcuts.
> 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
> SciPy-User mailing list
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