How do I create histogram for a discrete probability distribution?

Hi, 

I am relatively new to Maple and I am seeking an efficient way to create a probability histogram for a discrete probability distribution. For example,

x:      1     3   5    7

p(x): 1/8 1/4 1/2 1/8

I would like rectangles with height corresponding to the probabilities with bases centered at each x value, allowing for the possibility of gaps in the distribtuion.

 Any ideas would be much appreciated, thanks!