Plotting irregular 2d data

Community matplotlib-users
1

Hi,

I have a 1d array Z that unfortunately contains information about a two
dimensional surface. The mapping is nontrivial (i.e. Z is not just a
sequence of column or row information that I could reshape) but
homogenous (i.e. there is a rectangular grid and Z contains data for
each vertex). The x and y coordinates for each datapoint in Z are
contained in separate arrays X and Y.

A simple pyplot.contour(X, Y, Z) refuses to plot the data because Z is
not 2d ("TypeError: Input z must be a 2D array").

What's the best way to plot this data?

Is there an easy way to reshuffle the elements of Z so that they are in
either row-column or column-row order?

Best,

   -Nikolaus

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2

Z = numpy.zeros((y_shape, x_shape))
x = your_flat_indices_in_x
y = your_flat_indices_in_y
z = your_flat_z_data

If you have only coordinates, then try to figure out the indices in
some way. Then do:

Z[zip(y, x)] = z

and figure out the coordinates that correspond to the mesh meant by Z.

It's "fancy indexing".

Z = numpy.zeros((2, 2))
x = numpy.asarray([0, 1])
y = numpy.asarray([0, 0])
z = numpy.asarray([10, 42])
Z[zip(y, x)] = z
Z

array([[ 10., 42.],
       [ 0., 0.]])

hth and is appropriate,
Friedrich