Incorporating a dummy date variable into a scatterplot

[Anthony Voyage]

Hey there,
I am trying to produce a graph that gives an indication of how two variables changes over time. One of the variables is recorded monthly (var_mm) and the other is recorded yearly (var_yy). I have a time-variable, date, on the x-axis. It is in the %d format (e.g. 21dec1994). I have a dummy variable, dummy, that is equal to either 1 or 0 for each month of date.

At the moment, I'm doing my basic graph as:

graph twoway (line var_mm var_yy date),

I would like to plot a line graph of var_mm and var_yy on date, but have vertical grey bars to indicate periods where dummy is equal to 1. Is this possible?

Thanks

[Clyde Schechter]

Well, I'm not that much of a graphics expert, and I don't know off hand how to do what you are asking for. But as an alternative that might have the same kind of visual impact, you might give a look at Nick Cox's -subsetplot- program, which you can get from SSC.

[Anthony Voyage]

Thank you Clyde, I'll have a look.

[Nick Cox]

Thanks to Clyde for mentioning subsetplot (SSC) but it sounds what is being sought here is different. Some technique is embedded in this reproducible example

 
set scheme s1color 
webuse grunfeld, clear 
su invest if company == 3 
gen bartop = 50 * ceil(r(max)/50) 
gen high = D.invest/invest > 0.4
twoway (bar bartop year if high,  bcolor(gs14)) (line invest year) if company == 3, ytitle(invest) legend(off)

In Anthony's case, if I understand correctly, the bars should be drawn with something like barw(30) as they correspond to months and the time axis shows a daily date.