How do I tell matplotlib that I am done with a plot?

The following code plots to two PostScript (.ps) files, but the second one contains both lines.

import matplotlib
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

plt.subplot(111)
x = [1,10]
y = [30, 1000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("first.ps")


plt.subplot(111)
x = [10,100]
y = [10, 10000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("second.ps")

How can I tell matplotlib to start afresh for the second plot?

There is a clear figure command, and it should do it for you:

plt.clf()

If you have multiple subplots in the same figure

plt.cla()

clears the current axes.

You can use figure to create a new plot, for example, or use close after the first plot.

As stated from David Cournapeau, use figure().

import matplotlib
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

plt.figure()
x = [1,10]
y = [30, 1000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("first.ps")


plt.figure()
x = [10,100]
y = [10, 10000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("second.ps")

Or subplot(121) / subplot(122) for the same plot, different position.

import matplotlib
import matplotlib.pyplot as plt
import matplotlib.mlab as mlab

plt.subplot(121)
x = [1,10]
y = [30, 1000]
plt.loglog(x, y, basex=10, basey=10, ls="-")

plt.subplot(122)
x = [10,100]
y = [10, 10000]
plt.loglog(x, y, basex=10, basey=10, ls="-")
plt.savefig("second.ps")

Just enter plt.hold(False) before the first plt.plot, and you can stick to your original code.