[R] Adding a legend to a (multi-facet) plot produced by ggplot().

[Rui Barradas]

Hello,

See if this is it. The standard trick is to reshape the data from wide 
to long, see the SO post [1]. Then add a scale_shape_* layer to the plot.


yyy <- cbind(xxx, y3 = y3)
long <- reshape2::melt(yyy, id.vars = c("x", "y1", "grp"))

ggplot(long, aes(x, y = value, colour = variable, shape = variable)) +
   geom_line(aes(y = y1)) +
   geom_point() +
   scale_colour_manual("Doesn't work",values=c("blue","red"),
                       labels=c("clyde","irving")) +
   scale_shape_manual("Doesn't work",values=c(16,3),
                       labels=c("clyde","irving")) +

   facet_grid(cols=vars(grp))


[1] 
https://stackoverflow.com/questions/2185252/reshaping-data-frame-from-wide-to-long-format

Hope this helps,

Rui Barradas

Às 00:04 de 01/12/19, Rolf Turner escreveu:
> 
> I have been struggling to add a legend as indicated in the subject line,
> with no success at all.  I find the help to be completely bewildering.
> 
> I have attached the code of what I have tried in the context of a simple
> reproducible example.
> 
> I have also attached a pdf file of a plot produced with base graphics to 
> illustrate roughly what I am after.
> 
> I would be grateful if someone could point me in the right direction.
> 
> cheers,
> 
> Rolf Turner
> 
> 
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