matplotlib contour/pcolor/pcolormesh/imshow
(x,y) values of the contour line
python - How can I get the that is plotted by a contour plot? - Stack Overflow
https://stackoverflow.com/questions/1560424/how-can-i-get-the-x-y-values-of-the-line-that-is-plotted-by-a-contour-plot
numpy - Python: find contour lines from matplotlib.pyplot.contour() - Stack Overflow
https://stackoverflow.com/questions/18304722/python-find-contour-lines-from-matplotlib-pyplot-contour
Difference
matplotlib: difference between pcolor, pcolormesh and imshow | Thomas Cokelaer's blog
http://thomas-cokelaer.info/blog/2014/05/matplotlib-difference-between-pcolor-pcolormesh-and-imshow/
MetPy Mondays '#121 - What's the difference between imshow, pcolor, and pcolormesh? : Unidata Developer's Blog
https://www.unidata.ucar.edu/blogs/developer/entry/metpy-mondays-121-what-s
transparency
python - Matplotlib Contourf Plots Unwanted Outlines when Alpha < 1 - Stack Overflow
https://stackoverflow.com/questions/15192661/matplotlib-contourf-plots-unwanted-outlines-when-alpha-1
python - I want my contourf semi-transparent, but my colorbar not - Stack Overflow
https://stackoverflow.com/questions/34744876/i-want-my-contourf-semi-transparent-but-my-colorbar-not