How to replace tick labels for an image displayed with matplotlib

change_imshow_ticks.py

#!/usr/bin/env python

"""
Demonstrate how to replace tick labels for a displayed image.
"""

import numpy as np
import pylab as pl

im = np.random.rand(100, 200)
pl.imshow(im, origin='lower')
x = np.linspace(0, 1000, len(pl.xticks()[0]-1))
y = np.linspace(5, 2500, len(pl.yticks()[0]-1))

# Discard the first location because it's label is empty:
locs, labels = pl.xticks()
pl.xticks(locs[1:], map(lambda f: '%3.2e' % f, x))
locs, labels = pl.yticks()
pl.yticks(locs[1:], map(lambda f: '%3.2e' % f, y))
pl.show()