How to visualize scalar 2D data with Matplotlib?

Question

So i have a meshgrid (matrices X and Y) together with scalar data (matrix Z), and i need to visualize this. Preferably some 2D image with colors at the points showing the value

Answer 1

If your meshgrid has uniform spacing, you could continue to use pcolor, but just shift X and Y for the purposes of centering the data at the particular values rather than at the corners.

You could also use a scatter plot to explicitly place points of some size at the exact X and Y points and then set the color to Z:

x = numpy.arange(10)
y = numpy.arange(10)
X,Y = numpy.meshgrid(x,y)
Z = numpy.arange(100).reshape((10,10))
scatter(X,Y,c=Z,marker='s',s=1500) 
#I picked a marker size that basically overlapped the symbols at the edges
axis('equal')

or:

pcolor(X+0.5,Y+0.5,Z)
axis('equal')

or as Paul suggested, using one of the contour functions