Graph's naming rule and Stata reports error

[Chen Samulsion]

Dear Stata users,

My question is about graph's naming rule in Stata. After many tries, I know now that there should be no blank when naming a Stata graph. I wonder is there someone can provide a complete naming rule in Stata. See below for some examples.

sysuse auto, clear
label var mpg "Mileage(mpg)12To41"
graph drop _all
foreach v of varlist price rep78 mpg {
 local name: variable label `v'
 local nname: word 1 of `name'
 graph hbar (mean) `v', over(foreign, sort(1) descen) title("`nname'") name("`nname'")
 }

( invalid name
) invalid name
12To41 invalid name
r(198);

[Nick Cox]

I don't think I have thought about this, but I don't think that experience contradicts a guess that graph names are governed by the same rules as names in general. See [U] 11.3.

[Chen Samulsion]

Nick, thank you all the same. I think this is a trivial matters. I post this thread only because in a loop I want to use variables' label which are composed of multiple piece of word as graphs' name, and the existing naming rule leave me some (a trifle) inconvenience.

[Nick Cox]

strtoname() exists for your purpose of taking arbitrary strings and producing legal names.

. di strtoname("Chen is puzzled")
Chen_is_puzzled

[Chen Samulsion]

Dear Nick Cox, nice and humorous answer! The codes above run successfully after inserting strtoname() function. Thank you so much!

sysuse auto, clear
label var mpg "Mileage(mpg)12To41"
graph drop _all
foreach v of varlist price rep78 mpg {
 local name: variable label `v'
 local nname=strtoname("`name'")
 graph hbar (mean) `v', over(foreign, sort(1) descen) title("`nname'") name("`nname'")
 }