How to set "step" on x-axis in my figure in matplotlib

I have some code: ``` #!/usr/bin/env python import matplotlib matplotlib.use("Agg") import matplotlib.pyplot as plt x = [1,2,3,4,5] y = [1.2,1.9,3.1,4.2,4.8] plt.plot(x,y) plt.xlabel('OX') plt.ylabel('OY') plt.savefig('figure1.png') plt.close() ``` And it gives me that figure: As you can see, the "step" on axis X is 0.5 but I would like to set it to 1. How to make it? When I use `plt.xticks(1)`, it gives me errors: ``` Traceback (most recent call last): File "overflow.py", line 13, in <module> plt.xticks(1) File "/usr/lib/pymodules/python2.6/matplotlib/pyplot.py", line 998, in xticks locs = ax.set_xticks(args[0]) File "/usr/lib/pymodules/python2.6/matplotlib/axes.py", line 2064, in set_xticks return self.xaxis.set_ticks(ticks, minor=minor) File "/usr/lib/pymodules/python2.6/matplotlib/axis.py", line 1150, in set_ticks if len(ticks) > 1: TypeError: object of type 'int' has no len() ``` I use Python 2.6.6 on Ubuntu 10.10.