Multiple lines for values of a variable on a graph

[Dick Campbell]

I am working on Covid from various counties and regions in a particular US State. In order to get trend lines for several counties on a single graph I have written code like the following:

twoway (line cum_case_n day_ob if county == "Brown", sort) ///
    (line cum_case_n day_ob if county == "Racine", sort) ///
    (line cum_case_n day_ob if county == "Milwaukee", sort) ///
    (line cum_case_n day_ob if county == "Forest", sort) ///
    (line cum_case_n day_ob if county == "Polk", sort), ///

I have omitted the remaining title lines etc.

While this works it is a bit tedious and I keep thinking there has to be a simpler way to do it. A by statement produces separate subgraphs. I thought there might be an over options so that one could get multiple lines on the same plot with a single graph spec but that doesn't seem to be the case. Is there any easier way to do this?

[Andrew Musau]

You can encode the counties, xtset the data and use xtline.

webuse grunfeld, clear
xtset company year
xtline mvalue if inlist(company, 1, 5, 7, 8, 9), overlay scheme(s1color)

[Dick Campbell]

Thank very much! I was so focused on this as a twoway problem that I didn't see that xtline was a simple solution. Duh....