Plotting Edgeworth Box, or else locating axes origin north-east


I have a problem I tried to solve in any way,a nd couldn't.
I want to plot an Edgeworth Box with matplotlib.

To do so, I need to create a plot with origin on the north-east corner with
axes scales going "the wrong way". For an idea of how an EB works, see:

I noticed that


allows me to make the scale go backwards from 1 to 0.
I just need a way to put the origin on the upper-right corner. I couldn't find
one, I could just set the origin up-left (north-west), bot not up-right

Any help would be highly appreciated.

Thanks for the great app.