[Numpy-discussion] numpy.array does not take generators
Robert Kern
robert.kern at gmail.com
Fri Aug 17 02:19:53 EDT 2007
Geoffrey Zhu wrote:
> Hi All,
>
> I want to construct a numpy array based on Python objects. In the
> below code, opts is a list of tuples.
>
> For example,
>
> opts=[ ('C', 100, 3, 'A'), ('K', 200, 5.4, 'B')]
>
> If I use a generator like the following:
>
> K=numpy.array(o[2]/1000.0 for o in opts)
>
> It does not work.
>
> I have to use:
>
> numpy.array([o[2]/1000.0 for o in opts])
>
> Is this behavior intended?
Yes. With arbitrary generators, there is no good way to do the kind of
mind-reading that numpy.array() usually does with sequences. It would have to
unroll the whole generator anyways. fromiter() works for this, but you are
restricted to 1-D arrays which is a lot easier to implement the mind-reading for.
--
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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