[Numpy-discussion] MaskedArray problem?

[T. C. <al...@an...>]

Hello,

I'm trying to rewrite my simulation using masked arrays. For that I
define masks for triangular_inferior NxN and
diagonal_triangular_superior NxN arrays.

I'm unsuccesfully trying to know what happens with the program when I
operate over a MaskedArray: it always says

Traceback (most recent call last):
  File "<stdin>", line 31, in ?
  File "<stdin>", line 26, in run
  File "/usr/lib/python2.3/site-packages/numarray/ma/MA.py", line 990,
in __pow__
    return power(self, other, third)
  File "/usr/lib/python2.3/site-packages/numarray/ma/MA.py", line 1585,
in power
    return masked_array(Numeric.power(fa, fb), m)
  File "/usr/lib/python2.3/site-packages/numarray/ufunc.py", line 877,
in _cache_miss2
    mode, win1, win2, wout, cfunc, ufargs =3D \
  File "/usr/lib/python2.3/site-packages/numarray/ufunc.py", line 921,
in _setup
    intypes =3D (in1._type.name, in2._type.name)
AttributeError: 'ObjectArray' object has no attribute '_type'


For reference, I copy a simplified version of the program. The statement
that causes the AttributeError is the last from run(N,D,S):

---------------------------

import numarray.ma as mka
import numarray.random_array as rnd
import numarray as nmr

def relative(x, msk):
    (N,D) =3D x.shape
    return mka.array([nmr.subtract.outer(x[:,i],x[:,i]) for i in nmr.arange=
(D)],
                     mask =3D nmr.array([msk for i in nmr.arange(D)],typeco=
de=3Dmka.MaskType))

def scalar(x,y):
    return mka.add.reduce(x*y,axis=3D0)

def run(D,N,S):
    trig_inf =3D nmr.array(([[(0,1)[i<j] for i in nmr.arange(N)] for j in n=
mr.arange(N)]), typecode=3Dmka.MaskType)
    diag_trig_sup =3D 1 - trig_inf #print mka.is_mask(diag_trig_sup) gives =
"1"

    # positions and velocities
    r =3D rnd.random([N,D]) #should be overlap-checked
    v =3D rnd.random([N,D])

    # relative positions and velocities
    r_rel =3D relative(r, diag_trig_sup)
    v_rel =3D relative(v, diag_trig_sup)

    RV, VV, RR =3D scalar(r_rel,v_rel), scalar(v_rel,v_rel), scalar(r_rel,r=
_rel)
    discr =3D RV**2 - VV*(RR-S**2)      #<<<<----------PROBLEM HERE--------=
--------



if __name__ =3D=3D '__main__':
    run(D=3D3,N=3D4,S=3D1e-8)


-------------------------

Any other advice that you may give me is very wellcome. My deadline is
approaching and I'm really reluctant to rewrite all this in C++ but I
don't see the light.

Thank you in advance,

 =E1.


--=20
=C1lvaro Tejero Cantero

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