[Numpy-discussion] MaskedArray problem?
Álvaro Tejero Cantero
alvaro at antalia.com
Mon May 17 09:25:05 CDT 2004
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 = \
File "/usr/lib/python2.3/site-packages/numarray/ufunc.py", line 921,
in _setup
intypes = (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) = x.shape
return mka.array([nmr.subtract.outer(x[:,i],x[:,i]) for i in nmr.arange(D)],
mask = nmr.array([msk for i in nmr.arange(D)],typecode=mka.MaskType))
def scalar(x,y):
return mka.add.reduce(x*y,axis=0)
def run(D,N,S):
trig_inf = nmr.array(([[(0,1)[i<j] for i in nmr.arange(N)] for j in nmr.arange(N)]), typecode=mka.MaskType)
diag_trig_sup = 1 - trig_inf #print mka.is_mask(diag_trig_sup) gives "1"
# positions and velocities
r = rnd.random([N,D]) #should be overlap-checked
v = rnd.random([N,D])
# relative positions and velocities
r_rel = relative(r, diag_trig_sup)
v_rel = relative(v, diag_trig_sup)
RV, VV, RR = scalar(r_rel,v_rel), scalar(v_rel,v_rel), scalar(r_rel,r_rel)
discr = RV**2 - VV*(RR-S**2) #<<<<----------PROBLEM HERE----------------
if __name__ == '__main__':
run(D=3,N=4,S=1e-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,
á.
--
Álvaro Tejero Cantero
http://alqua.org -- documentos libres
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