Transparency in tw bar

[Adam Ansel]

Hi All,

I've come across a problem in Stata 17 which looks to me like a bug. I tried to set the transparency for a twoway bar with the color option, but it only affects one of the bars. Here is an MWE:

sysuse auto, clear
bysort rep78: egen mpg_avg = mean(mpg)

tw bar mpg_avg rep78, color(green)
// all bars are affected
tw bar mpg_avg rep78, color(%25)
// only the first bar is affected
tw bar mpg_avg rep78, fcolor(%25)
// same problem
tw bar mpg_avg rep78, fcolor(green) lcolor(black%25)
// Outlines of all bars are affected

The same problem arises using the fcolor option, but not for the lcolor option.

Is that my mistake or a bug?

All best.

[Hua Peng (StataCorp)]

It is not a bug. You have multiple bars at the same location. Try

 
 tw bar mpg_avg rep78, color(%2)

[Nick Cox]

Here is one way to plot each bar just once.

egen tag = tag(rep78)  tw bar mpg_avg rep78 if tag

[Adam Ansel]

Thank you very much!