# st: AW: RE: bar graph with 2 y-axes

 From Jochen Späth To Subject st: AW: RE: bar graph with 2 y-axes Date Mon, 27 Apr 2009 15:28:59 +0200

```Hello Nick and Martin,

thank you very much. Although the solution is simple, it is somewhat tricky and I did not find it myself :-)

Yours,
Jochen

-----Ursprüngliche Nachricht-----
Von: owner-statalist@hsphsun2.harvard.edu [mailto:owner-statalist@hsphsun2.harvard.edu] Im Auftrag von Nick Cox
Gesendet: Montag, 27. April 2009 15:16
An: statalist@hsphsun2.harvard.edu
Betreff: st: RE: bar graph with 2 y-axes

One way to proceed is splendidly ad hoc.

use http://www.stata-press.com/data/r10/friedman2.dta
gen year = yofd(dofq(time))
collapse m1 consump , by(year)
gen year1 = year - 0.2
gen year2 = year + 0.2
twoway bar consump year1, barw(0.4) || bar  m1 year2, barw(0.4)

(In this example, no doubt there is a case for a different kind of -collapse-, but it doesn't affect the graphical issue.)

Such age-old trickery was written up in

SJ-7-1  gr0026  . . . .  Stata tip 42: The overlay problem: Offset for clarity
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . J. Cui
Q1/07   SJ 7(1):141--142                                 (no commands)
tip for graphing several quantities on a continuous axis

Nick
n.j.cox@durham.ac.uk

Jochen Späth

After screening the statalist and some graphical advice literature in the last days I still haven't got the clue:
I need to draw a bar graph for two time series with different scales (e.g. one in millions, the other in billions) over years.
Graph bar delivers the desired over-all look as, f.i., in

-graph bar var1 var2,  over(year)-.

But I would like to have two different scales (left and right).
-graph bar- does not offer such an option with the -over-option - logically.
In -twoway bar-, which has the option for a second vertical axis as in

-graph twoway (bar var1 year, yscale(1)) (bar var2 year, yscale(2))-,

I have not managed to override the default result that the bars are drawn one behind the other - I rather want them one beside the other (and grouped over years).

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```