Plotting 2 Variables With A Heat Map

I'm on the python 3 and I have two variables x and y, where x ranges from 1 to 5 and y from 0.03 to 0.7 and I then have a method that takes x and y and generates a scalar number. I

Solution 1:

If you start with 2 mono-dimensional vectors, x and y to compute a function of x and y on a grid of 2D points you have first to generate said 2D grid, using numpy.meshgrid.

from numpy import linspace, meshgrid
x, y = linspace(1, 5, 41), linspace(0.03, 0.70, 68)
X, Y = meshgrid(x, y)

It's somehow a surprise to see that you get two grids... one contains only the x values and the other only the y values (you have just to print X and Y to see for yourself).

With these two grids available, you can compute a grid of results, but this works only when you use numpy's ufuncs... e.g.

def f(x, y):
    from numpy import sin, sqrt
    return sin(sqrt(x*x+y*y))

and eventually you can plot your results, the pyplot method that you want to use is pcolor, and to add a colorbar you have to use, always from pyplot, the colorbar method...

from matplotlib.pyplot import colorbar, pcolor, show
Z = f(X, Y)
pcolor(X, Y, Z)
colorbar()
show()

When this point is eventually reached, tradition asks for a sample output That's all

Solution 2:

Lets say z = f(x, y). Your heatmap's key is able to represent one dimension only (usually that would be z). What do you mean by

represent the method f(x,y)

For 2-dimensional plotting, you would need a 3-dimensional heatmap.