Stereographic sun chart matplotlib polar graph python

Question

I am trying to create a simple stereographic diagram of the trajectory of the sun similar to this: http://wiki.naturalfrequency.com/wiki/Sun-Path_Diagram

I can rotate the polar graph and set the scale to 90. How do I flip the y axis? Currently, the axis goes from 0> 90, how to change the axis to 90> 0 to represent the azimuth?

I tried:

ax.invert_yaxis() ax.yaxis_inverted() 

Further, how would I like to create a stereographic projection, rather than an equidistant projection?

My code is:

 import matplotlib.pylab as plt testFig = plt.figure(1, figsize=(8,8)) rect = [0.1,0.1,0.8,0.8] testAx = testFig.add_axes(rect,polar=True) testAx.invert_yaxis() testAx.set_theta_zero_location('N') testAx.set_theta_direction(-1) Azi = [90,180,270] Alt= [0,42,0] testAx.plot(Azi,Alt) plt.show() 

At present, my code doesn't seem to even build the lines correctly, will I need to convert the angle or degrees to something else?

Any help is greatly appreciated.

Answer 1

Finally, I managed to play with matplotlib. After a long search, the right approach, as Joe Kington points out, is to subclass axes. I found a much faster way to use an excellent base module.

Below is the code that I adapted for stackoverflow. The altitude and azimuth of the sun were calculated using Pysolar with a set of time stamps created in pandas.

 import matplotlib.pylab as plt from mpl_toolkits.basemap import Basemap import numpy as np winterAzi = datafomPySolarAzi winterAlt = datafromPySolarAlt # create instance of basemap, note we want a south polar projection to 90 = E myMap = Basemap(projection='spstere',boundinglat=0,lon_0=180,resolution='l',round=True,suppress_ticks=True) # set the grid up gridX,gridY = 10.0,15.0 parallelGrid = np.arange(-90.0,90.0,gridX) meridianGrid = np.arange(-180.0,180.0,gridY) # draw parallel and meridian grid, not labels are off. We have to manually create these. myMap.drawparallels(parallelGrid,labels=[False,False,False,False]) myMap.drawmeridians(meridianGrid,labels=[False,False,False,False],labelstyle='+/-',fmt='%i') # we have to send our values through basemap to convert coordinates, note -winterAlt winterX,winterY = myMap(winterAzi,-winterAlt) # plot azimuth labels, with a North label. ax = plt.gca() ax.text(0.5,1.025,'N',transform=ax.transAxes,horizontalalignment='center',verticalalignment='bottom',size=25) for para in np.arange(gridY,360,gridY): x= (1.1*0.5*np.sin(np.deg2rad(para)))+0.5 y= (1.1*0.5*np.cos(np.deg2rad(para)))+0.5 ax.text(x,y,u'%i\N{DEGREE SIGN}'%para,transform=ax.transAxes,horizontalalignment='center',verticalalignment='center') # plot the winter values myMap.plot(winterX,winterY ,'bo') 

Please note that currently I am only drawing points, you will need to make sure that the points on the line have a point at a height of 0 at sunrise / sunset.