st: appending graphs

["Lim, Raymond" <rl2240@columbia.edu>]

Hi Statalisters,
Is there a way to append graphs? I want to automate producing graphs by a categorical variable, with with different number of lines. 
For example, Say you are creating time series graph of GPA by school and by subject (subject 1...20, each school offering a combination of them). Thus for each school, you have a graph with 3 to 5 different lines representing GPA in different subjects across time. The command would be something along the lines of

#delimit ;
tsset school year;
twoway (tsline mean if school==1 & subject==7) 
	 (tsline mean if school==1 & subject==8) 
	 (tsline mean if school==1 & subject==9);
twoway (tsline mean if school==2 & subject==4) 
	 (tsline mean if school==2 & subject==8);
twoway (tsline mean if school==2 & subject==1) 
	 (tsline mean if school==2 & subject==2);

Etc...

I want to write a loop that will add lines to the graph as long as there are subjects that still need to graphed. I was thinking about using a for-loop, but I need to repeat "(tsline mean if school==__ & subject==__)" until all the subjects are accounted for.

Thanks for any input!
-Raymond

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