Python matplotlib restrict to integer tick locations

Question

Quite often I want to make a bar chart of counts. If the counts are low I often get major and/or minor tick locations that are not integers. How can I prevent this? It makes

Answer 1

 pylab.bar(range(1,4), range(1,4), align='center')  

and

 xticks(range(1,40),range(1,40))

has worked in my code. Just use the align optional parameter and xticks does the magic.