Does pcolormesh plot the 2D array rightside-up or upside-down?
The array is plotted upside-down, meaning the index (0, 0) is at the bottom left.
Every time I go to plot a 2D array in matplotlib using, for example, pcolormesh, I have the same question: Is the resultant image showing the array rightside-up or upside-down?  That is, is index (0, 0) at the top left of the plot or the bottom left?
It's tedious to write a test every six months to remind myself.  This should be clearly documented in an obvious place, like SO.