Graph with 2 bars, 2 lines and 2 y-axes

[Patrick Zollner]

Hello, my data consists of binned observations which contain counts organized by year, engine and costs.

I am trying to merge two graphs with two axes into one. Here is the code I have used to produce the three graphs below:

graph twoway (bar counts bin_e if engine == 1 & year == 2015, yaxis(1)) ///
(line cost bin_e if engine == 1 & year == 2015, sort yaxis(2) xline(82 110 160 180, lpattern(dash) lc(gray)))

 
graph twoway (bar counts bin_e if engine == 2 & year == 2015, yaxis(1)) ///
    
(line cost bin_e if engine == 2 & year == 2015, sort yaxis(2) xline(82 110 160 180, lpattern(dash) lc(gray)))

 
graph twoway (bar counts bin_e if engine == 1 & year == 2015, yaxis(1)) ///
    
(bar counts bin_e if engine == 2 & year == 2015, yaxis (1)) ///
    
(line cost bin_e if engine == 1 & year == 2015 , sort yaxis(2) lc(navy) xline(82 110 160 180, lpattern(dash) lc(gray))) ///
    
(line cost bin_e if engine == 2 & year == 2015, sort yaxis(2) lc(maroon)), ///
    
legend ( ///
    
label(1 count a) label(2 count b) label(3 cost a) label(4 cost b))

The result is close to what I want, but I would like the bars next to each other instead of on top of each other. I have tried combining commands like graph (bar x, over y (asyvars) z) with (twoway line) to no avail. Separately, I get graphs that look like they're getting to the right place, but together it doesn't seem to work. A common error I get is '( bargraph_g invalid name' for code similar to the following:

graph (bar counts if inlist(engine, 1, 2) & year == 2015, over(engine) asyvars over(bin_e)) ///
(twoway line costs bin_e, sort yaxis(2) xline(82 110 160 180, lpattern(dash))) if engine == 1 & year == 2015

Additionally, I'd like to ask how I should refer to the two y-axes in the code when changing their titles, labels, ticks, ranges etc.

Much thanks in advance!

[Patrick Zollner]

I played around with it a bit and eventually settled on creating two new variables: bin_e+0.7 and bin_e-0.7 and using those. If you have a more elegant solution I'd still love to hear it.