No plot window in matplotlib

I just installed matplotlib in Ubuntu 9.10 using the synaptic package system. However, when I try the following simple example

>>> from pylab import plot;
>>> plot([1,2,3],[1,2,3])
[<matplotlib.lines.Line2D object at 0x9aa78ec>]

I get no plot window. Any ideas on how to get the plot window to show?

Solution 1:

You can type

import pylab
pylab.show()

or better, use ipython -pylab.

Since the use of pylab is not recommended anymore, the solution would nowadays be

import matplotlib.pyplot as plt

plt.plot([1,2,3])

plt.show()

Solution 2:

pylab.show() works but blocks (you need to close the window).

A much more convenient solution is to do pylab.ion() (interactive mode on) when you start: all (the pylab equivalents of) pyplot.* commands display their plot immediately. More information on the interactive mode can be found on the official web site.

I also second using the even more convenient ipython -pylab (--pylab, in newer versions), which allows you to skip the from … import … part (%pylab works, too, in newer IPython versions).