Why does numpy.array(a,b) have this meaning?
robert.kern at gmail.com
Mon Nov 3 18:42:52 CET 2008
Rick Giuly wrote:
> Hello All,
> Case 1
> This generates an error, which makes sense because the argument should
> be a list of numbers:
> Case 2
> This does not generate an error and the result is an array with a
> single element:
> a = numpy.array()
> b = numpy.array()
> The only different I see here between the numpy.array call in the
> cases is that
> a is a numpy int32
> 10 is an int
> Why would this minor difference in integer types cause a totally
> different result for the two cases - or is something else causing the
> difference in results?
The second argument is for a dtype. Basically, we'll accept anything there that
can be coerced to a dtype using numpy.dtype(). For some reason, we have an
undocumented feature where dtype(some_array_or_numpy_scalar) will return the
dtype of that value. Plain Python ints and floats don't have a dtype attached to
them, so we raise an exception.
If you have more numpy questions, please join us on the numpy-discussion mailing
"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
More information about the Python-list