I'm using the command

histogram [cat var]

to output a histogram in stata. I only care about the values of the categorical variable which are greater than 0, but there are some negative values and they also show up in the histogram. I understand that I could drop those values and then generate the histogram again (and I have done that and seen it work), but I am wondering if I could restrict the histogram to when the values are greater than 0 during its generation.