[Numpy-discussion] indexing of rank-0 structured arrays: why not?

Robert Kern robert.kern at gmail.com
Mon Jan 10 12:05:45 EST 2011

On Mon, Jan 10, 2011 at 10:08, Nils Becker <n.becker at amolf.nl> wrote:
> Hi,
> I noticed that I can index into a dtype when I take an element
> of a rank-1 array but not if I make a rank-0 array directly. This seems
> inconsistent. A bug?

Not a bug. Since there is no axis, you cannot use integers to index
into a rank-0 array. Use an empty tuple instead.

|1> dt = np.dtype([('x', '<f8'), ('y', '<f8')])

|2> a_rank_0 = np.zeros((), dtype=dt)

|3> a_rank_0[()]
(0.0, 0.0)

Robert Kern

"I have come to believe that the whole world is an enigma, a harmless
enigma that is made terrible by our own mad attempt to interpret it as
though it had an underlying truth."
  -- Umberto Eco

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