PyPlot reverse Y-Axis

Question

I have a scatter plot graph with a bunch of random x,y coordinates. Currently the Y-Axis starts at 0 and goes up to the max value. I would like the Y-Axis to start at the max value and go up to 0.

points = [(10,5), (5,11), (24,13), (7,8)]    
x_arr = []
y_arr = []
for x,y in points:
    x_arr.append(x)
    y_arr.append(y)
plt.scatter(x_arr,y_arr)

Answer 1

Use matplotlib.pyplot.axis()

axis([xmin, xmax, ymin, ymax])

So you could add something like this at the end:

plt.axis([min(x_arr), max(x_arr), max(y_arr), 0])

Although you might want padding at each end so that the extreme points don't sit on the border.

Answer 2

DisplacedAussie's answer is correct, but usually a shorter method is just to reverse the single axis in question:

plt.scatter(x_arr, y_arr)
ax = plt.gca()
ax.set_ylim(ax.get_ylim()[::-1])

where the gca() function returns the current Axes instance and the [::-1] reverses the list.