CODEWITHSUNDEEP
loopsgraphstatalegend
Kiefer
Kiefer

Reputation: 163

Create graph legend inside loop in Stata

I would like to generate graphs for different datasets, with the same variables, but in which the years change. So far I can generate the graphs, without a legend, doing this:

levelsof year, local(lyear)
foreach l of local lyear {
    local fig `fig' scatter mpg time if year==`l', connect(l) ||    
}
graph twoway `fig'

I want to add a legend showing each year. For example, doing it without a loop, I would add the option:

graph twoway `fig',  legend(lab(1 "2010") lab(2 "2011") lab(3 "2012"))

Is there a way to have the years appear in the legend as part of a loop? The years, and the number of years, change from dataset to dataset and this would be helpful.

Upvotes: 0

Views: 923

Answers (2)

drstevok
drstevok

Reputation: 715

This is not a comment on the (presumably better) answer above, but for future reference you can do all sorts of marvellous things with local macros. Just build a loop that updates the year (or anything else), then put this in a macro and use the macro for the options.

Here's a snippet from an example that I used to generate rug plots in Stata. 

    foreach llevel of local llevels {
        local pposition: list posof "`llevel'" in llevels
        local rposition = `ssize'-`pposition'+1
        local iintensity=1-(0.7*((`rposition')/`maxlevels'))
        local rrug "`rrug' (scatter rugzero `rugvar'" 
        local rrug "`rrug' if `rugvar'_pickone &"
        local rrug "`rrug' `rugvar'_cat==`llevel' & `my_touse',"
        local rrug "`rrug' xaxis(`axis') msymbol(none) mlab(ruglabel)"
        local rrug "`rrug' mlabcolor(*`iintensity')"
        local rrug "`rrug' mlabposition(`clock') )"

    }

Upvotes: 1

Nick Cox
Nick Cox

Reputation: 37208

My short answer is that I would not draw such a graph with a loop at all.

Here is one way to do it: 

separate mpg, by(year) veryshortlabel 
twoway connected `r(varlist)' time, sort

Here is another way to do it: 

ssc inst sepscatter 
sepscatter mpg time, sep(year) recast(connected) sort

You need only install sepscatter once.

Detail: this 

legend(lab(1 "2010") lab(2 "2011") lab(3 "2012"))

is easier as 

legend(order(1 "2010" 2 "2011" 3 "2012"))

Upvotes: 2

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