Retrieving information on graph elements

[Johan Karlsson]

Dear Statalist,

Is there any way to access the information in Stata on the edges of different graph elements?

For my specific purposes, I am for example working with graphs presented as dials, where I would like to be able to overlay the indicator on the dial with a line and an arrow tip (example below).
The "indicator" in this case is a thin piece of pie chart. If I could retrieve information on the edges of it, I should be able to overlay it with a line.

Any help on this would be greatly appreciated.

Sincerely
Johan

[Maarten Buis]

Are you creating these graphs in Stata or are the "data" you have received outside Stata?

[Johan Karlsson]

Are you creating these graphs in Stata or are the "data" you have received outside Stata?

The graphs are all made in Stata. The backdrop is made from a pie chart with the lower half hidden, and the "indicator" is done by piggybacking off the "angle" option on the pie charts. Both are added together using graph combine, and where the indicator is dragged over to the backdrop.

[Scott Merryman]

This is not about retrieving information from a pie chart, but here is way to create a dial graph using Asjad Naqvi's -sunburst- to get the half pie chart.

serset drop _all
cwf default
frame drop f*
sysuse auto,clear
quietly tab rep
local groups = r(r) - 1

//Using Asjad Naqvi's sunburst to half circle sectors
sunburst mpg if rep !=., by(rep) cfill(none) clw(0) share labsize(2)

serset dir
forvalues i = 0/`groups' {
    frame create f`i'
    frame change f`i'
    serset set `i'
    serset use
    gen group = `i'
    keep x y group
}
frame change f0
//Using Jürgen Wiemers' fframeappend
//ssc desc fframeappend
fframeappend , using(f1 f2 f3 f4)

sum x, meanonly
local radius = r(max)

//Note angle starts at 0 on the right side
twoway area y x if group == 0 , nodropbase ///     
    || area y x if group == 1 , nodropbase ///     
    || area y x if group == 2 , nodropbase ///     
    || area y x if group == 3,  nodropbase ///     
    || area y x if group == 4 , nodropbase /// 
    || pcarrowi  0 0  `=`radius'*sin(135*_pi/180)' `=`radius'*cos(135*_pi/180)', /// 
            lw(*2) lc(black) mcolor(black)  /// 
    || , legend(off) yscale(off) xscale(off) aspect(0.5) xsize(2) ysize(1) /// 
        xlabel(-10 10, nogrid) ylabel(0 10, nogrid)

[Johan Karlsson]

This is not about retrieving information from a pie chart, but here is way to create a dial graph using Asjad Naqvi's -sunburst- to get the half pie chart.

serset drop _all
cwf default
frame drop f*
sysuse auto,clear
quietly tab rep
local groups = r(r) - 1

//Using Asjad Naqvi's sunburst to half circle sectors
sunburst mpg if rep !=., by(rep) cfill(none) clw(0) share labsize(2)

serset dir
forvalues i = 0/`groups' {
frame create f`i'
frame change f`i'
serset set `i'
serset use
gen group = `i'
keep x y group
}
frame change f0
//Using Jürgen Wiemers' fframeappend
//ssc desc fframeappend
fframeappend , using(f1 f2 f3 f4)

sum x, meanonly
local radius = r(max)

//Note angle starts at 0 on the right side
twoway area y x if group == 0 , nodropbase ///
|| area y x if group == 1 , nodropbase ///
|| area y x if group == 2 , nodropbase ///
|| area y x if group == 3, nodropbase ///
|| area y x if group == 4 , nodropbase ///
|| pcarrowi 0 0 `=`radius'*sin(135*_pi/180)' `=`radius'*cos(135*_pi/180)', ///
lw(*2) lc(black) mcolor(black) ///
|| , legend(off) yscale(off) xscale(off) aspect(0.5) xsize(2) ysize(1) ///
xlabel(-10 10, nogrid) ylabel(0 10, nogrid)

[ATTACH=CONFIG]n1748916[/ATTACH]

That's really helpful, thank you!