[Matplotlib-users] pcolormesh - bus error Numeric - bug

[James B. <bo...@ll...>]

Thanks for the replies - since it worked Ok for other people I looked a 
bit further:

matplotlib 0.87.2,   OS X  10.3.9,    Numeric - 23.7,  ipython 0.6.15

  running quadmesh_demo.py in examples gives a bus error when the figure 
is rendered.

It turns out that the collections object returned by the line 16 of 
quadmesh_demo.py:
ax.pcolormesh(Qx,Qz,Z)

returns vertices with complex values i.e.
b = ax.pcolormesh(Qx,Qz,Z)
c= b._coordinates
c[0]
Out[23]: [ 1.10000002+0.j,-1.99498999+0.j,]

this happens right away in pcolormesh since _coordinates are set there.
If I  force a type cast  as in:
b._coodinates = b._coodinates.astype(Numeric.Float32)
all goes well

  I suspected that something was screwy in lines of pcolormesh (lines 
2422 - 2326) in axes.py:
         coords = zeros(((Nx * Ny), 2),"Float32")
         # Numeric and numpy refuse to cast the Float64 arrays
         # to Float32 with simple assignment, so we do it explicitly.
         coords[:, 0] = X.astype(Float32)
         coords[:, 1] = Y.astype(Float32)

  it appears to be OK for a Float32 BUT if there is a string 
representation "Float32'"  the Numeric module  takes only the first 
character in this case an 'F' which implies complex for Numeric.
all appears OK for numarray and numpy.

---Jim