Lines on scatterplot: how not to include them in the legend?

[Mike Smet]

Hello,

I want to add some lines to divide a scatterplot in zones, e.g. via twoway pci.
See example below:

sysuse auto
scatter price mpg, xline(22.5) || (pci 10000 22.5 10000 42)

However, on the graph, I only want the legend for the dots ("Price") to appear below the graph, and not the "y/yb" for the horizontal line.
I tried the following command, but then the entire legend disappears ...

twoway (scatter price mpg, xline(22.5) legend(on)) || (pci 10000 22.5 10000 42, legend(off))

Does anyone has an idea how to solve this issue?

[Andrew Musau]

There are no multiple legends in a twoway graph, so you need the -order()- suboption to include or exclude plots.

legend(order(1))

[Mike Smet]

Wow, works fantastic!
Thank you very much.

[Nick Cox]

I would omit the legend here. Once you add ytitle(Price (USD)) it is superfluous. Very likely you would want to explain the added lines in a caption in Word or LaTeX or whatever, but that's a different story.

[Mike Smet]

Nick Cox The example I provided in #1 was indeed a bit too simplistic (with a superfluous legend) ... My actual problem was more something like this:

sysuse auto
separate price, by(foreign) shortlabel
scatter price? mpg, xline(22.5) || (pci 10000 22.5 10000 42)

resulting in this graph

The solution proposed in #2 ...

scatter price? mpg, xline(22.5) || (pci 10000 22.5 10000 42), legend(order(1 2))

... results in this graph (what I was looking for):

[Nick Cox]

I suggest

 
 separate price, by(foreign) veryshortlabel

as explained in https://www.stata-journal.com/sjpdf....iclenum=gr0023 (see also https://www.statalist.org/forums/for...lable-from-ssc).

[Mike Smet]

That's much nicer, indeed ... Thank you.