st: How do I draw graphs of injection history for 500 drug injectors ?

[André Jeannin <Andre.Jeannin@inst.hospvd.ch>]

Hello list,

I have data on 500 drug injectors and their injection history:
- injector identificator (injectorID)
- for each injector: date of injection (date), number of injections on 
that day (n_inj). For the period under study, there are between 2 and 200 
days with injection(s) per injector.

In the the first step in the analysis of these data, I want to do a visual 
inspection of the injection profiles.

In stata this is what I want to do:
	by injectorID: graph twoway bar n_inj date, 
saving(filename_based_on_injectorID)

This doesn't work because graph does not allow 'by:'
Is it a clean and easy way to do this ?

Any help would be appreciated.

Thanks.

Andre
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