[Numpy-discussion] Array of size 'n' with common difference < 1

Christopher Barker Chris.Barker at noaa.gov
Fri Apr 29 17:15:34 EDT 2011

On 4/29/11 1:27 PM, Sebastian Haase wrote:

> Just for completeness, note this paragraph from the mgrid docs:
> However, if the step length is a *complex number* (e.g. 5j), then the
> integer part of its magnitude is interpreted as specifying the number
> of points to create between the start and stop values, where the stop
> value *is inclusive*.

OK -- for a kluge, I figure you could do complex, then take the real 
part, but I can't seem to get a complex grid to work at all:

In [37]: np.mgrid[(0+0j):(1+0j):(0.1+0j)]
Out[37]: array([], dtype=complex128)

What am I doing wrong?

Go it -- the docs could use some clarification here -- Actually, passing 
in a complex nubmer is a FLAG, indicating that the index means somethign 
different, but it's still doing everything with real numbers (floats). 
Wow, klunky API!

but here is what the OP would want:

np.mgrid[-60:90:((60.j+90.j)*4. + 1j)]

which is klunkier that linspace.

I'd have used two different function names for the different mgrid 
functionality, rather that than the complex kludge


Christopher Barker, Ph.D.

Emergency Response Division
NOAA/NOS/OR&R            (206) 526-6959   voice
7600 Sand Point Way NE   (206) 526-6329   fax
Seattle, WA  98115       (206) 526-6317   main reception

Chris.Barker at noaa.gov

More information about the NumPy-Discussion mailing list