Separate legend for colour of two geoms

Xie Chao

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Mar 11, 2010, 5:27:48 AM3/11/10

to ggplot2

Hi,

I have two geoms in the same plot (point and segment). They are both
coloured, but based on different variables. My problem is that the
legend for colour is grouped together. Is there any easy way to get
separate legend for the two geoms? Thanks a lot.

#############################
pc <- prcomp(iris[,1:4], scale=T)
rotation <- data.frame(pc$rotation)
df <- data.frame(predict(pc))
df$species <- iris$Species

q <- qplot(PC1, PC2, data=df, colour=species) + coord_equal()
q + geom_segment(aes(0, 0, xend=PC1, yend=PC2,
colour=rownames(rotation)), rotation,
arrow=arrow(length=unit(0.2, 'cm')))
##############################

Best Regards,
Xie Chao

hadley wickham

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Mar 12, 2010, 8:50:10 AM3/12/10

to Xie Chao, ggplot2

Hi Xie,

Sorry, that's not currently possible. Each scale only produces a
single legend.

Hadley

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Nicholas Nagle

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Mar 12, 2010, 9:06:36 AM3/12/10

to hadley wickham, Xie Chao, ggplot2

As a complicated hack, would it be possible to do something like

q1 <- qplot(PC1, PC2, data=df, colour=species) + coord_equal()
q1.legend <- q1 + opts(keep= "legend_box")
q1 <- q1 + opts(legend.position='none')

q2 <- ggplot()+ geom_segment(aes(0, 0, xend=PC1, yend=PC2,

colour=rownames(rotation)), rotation, arrow=arrow(length=unit(0.2,
'cm')))

q2.legend <- q2 + opts(keep= "legend_box")
q2 <- q2 + opts(legend.position='none')

q <- q1+q2 # Not sure about this step, but the idea is to get both
plots on the same page without any legends.

and then use grid with three viewports, one for q, another for
q1.legend and the last for q2.legend?

Nicholas

takahashi kohske

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Mar 13, 2010, 3:41:34 AM3/13/10

to Nicholas Nagle, hadley wickham, Xie Chao, ggplot2

My workaround:

pc <- prcomp(iris[,1:4], scale=T)
rotation <- data.frame(pc$rotation)
df <- data.frame(predict(pc))
df$species <- iris$Species

# "main" layout without geom
q <- ggplot(df, aes(PC1, PC2))+opts(legend.position="none")+coord_equal()

# point geom whose color is specified by 'species'
q.g1<-geom_point(aes(colour=species))

# segment geom whose color is specified by 'rotation'
q.g2<-geom_segment(aes(0, 0, xend=PC1, yend=PC2,

colour=rownames(rotation)), rotation, arrow=arrow(length=unit(0.2,
'cm')))

grid.newpage()
pushViewport(viewport(layout = grid.layout(2, 2,
width=unit(c(3,1),c("null","null")))))

# "main" plot.
print(q+q.g1+q.g2,vp=viewport(layout.pos.col=1, layout.pos.row=1:2))

# legend for point geom
print(q+q.g1+opts(keep="legend_box",
legend.position=c(0.5,0.5)),vp=viewport(layout.pos.col=2,
layout.pos.row=1))
# legend for segment geom
print(q+q.g2+opts(keep="legend_box",
legend.position=c(0.5,0.5)),vp=viewport(layout.pos.col=2,
layout.pos.row=2))

HTH.

2010/3/12 Nicholas Nagle <nna...@utk.edu>:

Xie Chao

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Mar 13, 2010, 10:06:34 AM3/13/10

to takahashi kohske, Nicholas Nagle, hadley wickham, ggplot2

Thanks all for the help. Especially the opts(keep="legend_box").

Best Regards,
Xie Chao

Stéphane Laurent

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Oct 14, 2013, 2:47:18 PM10/14/13

to ggp...@googlegroups.com, Xie Chao

Wouldn't it be possible to create a new scale like "linecolor", which would allow to simultaneously have a color-based legend for lines and another color-based legend (for points for example) ?

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