Rotate entire y-axis 45 degrees (triangular plot) - Matplotlib

Question

What I have is:

But what I want is (paint mockup):

Is there any function matplotlib to perform this axis rotation? The code I used to produce the plot is this:

X = np.linspace(1 * 10**5, 100 * 10**5, 300)
Y = np.linspace(1 * 10**5, 100 * 10**5, 300)

fig = plt.contourf(X,Y,data,levels=10) # data is NaN for upper left triangle

plt.colorbar()
plt.savefig('output.png')

Answer 1

plt.yticks(rotation=45) should help for your case.