histogram bin widths

Hi All,

I am having trouble converting some histogram (hist) code written for an earlier version of matplotlib.
It uses the "width" keyword to set up fixed-width bins. However, I can't seem to recreate the exact plots, which is what I am trying to do - and the new rwidth parameter appears to be of no help, as it only allows me to set a scale factor.

Should I be using bins = [...] instead? If yes, has anyway tried converting bin widths from pre-rwidth versions of matplotlib before?

Many thanks,
Michael