The overlay point on top of the filled contour section adds a lot of free space

Question

I have the following Python code that I use to build a filled path:

def plot_polar_contour(values, azimuths, zeniths): theta = np.radians(azimuths) zeniths = np.array(zeniths) values = np.array(values) values = values.reshape(len(azimuths), len(zeniths)) r, theta = np.meshgrid(zeniths, np.radians(azimuths)) fig, ax = subplots(subplot_kw=dict(projection='polar')) ax.set_theta_zero_location("N") ax.set_theta_direction(-1) cax = ax.contourf(theta, r, values, 30) autumn() cb = fig.colorbar(cax) cb.set_label("Pixel reflectance") show() 

This gives me a plot like:

However, when I add the line ax.plot(0, 30, 'p') just before show() , I get the following:

It seems like just adding that one point (which is within the original axis range) spins the axis range on the radius axis.

Is it by design, or is it a mistake? What would you advise to do to fix this? Do I need to manually adjust the ranges of the axes, or is there a way to stop this additional command from executing?

Answer 1

If the axis autoscaling mode is not explicitly specified, plot will use “free” autoscaling, and contourf will use “tight” autoscaling.

The same thing happens for non-polar axes. For instance.

 import matplotlib.pyplot as plt import numpy as np plt.imshow(np.random.random((10,10))) plt.plot([7], [7], 'ro') plt.show() 

You have several options.

• Explicitly call ax.axis('image') or ax.axis('tight') at some point in the code.
• Go to scalex=False and scaley=False as the keyword arguments in plot .
• Manually set the axis limits.

The simplest and most readable is simply to call ax.axis('tight') , imo