Mplstereonet azimuth labels

Question

For my thesis I use the mplstereonet package to plot stereographic projections of points and planes obtained by using the ObsPy package. For my application I want to use azimuth labels that plot at a given angle outside of the circle. I am not using axis labels since they may overlap with possible data points in the centre of the circle.

The arguments of the set_azimuth_ticks function are:

1. positions of ticks around the circle in degrees
2. labels of ticks
3. distance of ticks from the circle. 1 is on, 0.9 is inside and 1.1 is outside the circle.

This is the code I use alongside my result: I obtain this result:

enter image description here

As you can see the labels are way too far from the circle.

import mplstereonet
import matplotlib.pyplot as plt

fig = plt.figure(figsize=(8,8))
ax = fig.add_subplot(111, projection='stereonet')
ax.grid()
ax.set_azimuth_ticks([0],['N'], frac = 0.9)

Answer 1

I was experiencing same issue as OP even in python3.7. My workaround, if labels are desired, uses ax.text with ax.transAxes transformation to position labels wrt plot axes. Remove bad labels as previous answer and add the following:

...
label = np.arange(0,360,45)
labx= 0.5-0.55*np.cos(np.radians(label+90))
laby= 0.5+0.55*np.sin(np.radians(label+90))
for i in range(len(label)):
            ax.text(labx[i],laby[i],str(int(label[i]))+'\N{DEGREE SIGN}', \
                    transform=ax.transAxes, ha='center', va='center')

Create a function with the code above if additional flexibility is needed. If you're plotting color bar or plot title you'll need to pad elements appropriately.

Answer 2

I am running python 3.9 and have the same issue with the ticks plotting way too far away from the axis. I found this workaround on the github site for this issue:

Add the line "ax._polar.set_position(ax.get_position())" before calling plt.show().

This resolved the issue. Hopefully they fix the code soon in mpl though

Answer 3

ax._polar.set_position(ax.get_position())

This worked perfectly for me. Although if you have subplots and want to set the distance between them, then there should be another work around to set the ticks at the new position of the subplots (see the image below).

original subplots with ax._polar.set_position(ax.get_position())

subplots with the new set distance

In that case I use the lines of code:

ax._polar.set_position(ax.get_position()) # to set the ticks
plt.subplots_adjust(right=0.5)

still looking for a work around for that and need to check the attributes of ax.get_position in detail.

Thanks!

Answer 4

I'm noticing a difference in behaviour between a python3.7 environment (which places the labels where I expect them) and a python 3.9 environment where they are too far out as the original poster observed. As a workaround, I am using this:

import mplstereonet as mpls
fig, ax = mpls.subplots(figsize=[5, 5])
ax.set_azimuth_ticks([])

just to remove the unsightly, bizarrely far away labels.