Two different color keys in ggplot

Question

I would like to plot points twice using two diferent color scales:

In the exemple here 5 points are drown and color is mapped to two covariates (cov1 and cov2): cov1 and cov2 are in different scales 1 to 5 and 0.01 to 0.05 respectively.

I wish to have 2 independent color keys, one for cov1 and one for cov2, a bit like in the graph below. However on the graph below I used 'color = cov1' end 'fill = cov2' in order to bring another color key...

Any help would be appreciated.

   gg1 <- ggplot(data = df1 , aes( x = x , y = y ) ) +
   geom_point( aes(x = x , y = y - 1 , color = cov1 ))  +
   geom_point( aes(x = x , y = y + 1 , color =  cov2  )) +
   scale_y_continuous(limits = c(-3,3)) 

  gg2 <- ggplot(data = df1 , aes( x = x , y = y ) ) +
  geom_point( aes(x = x , y = y - 1 , color = cov1 ))  +
  geom_point( aes(x = x , y = y + 1 , fill =  cov2  ), pch = 21 ) +
  scale_y_continuous(limits = c(-3,3)) 

grid.arrange( gg1 , gg2 , ncol = 2 )

Can you explain what you want to achieve that isn't achieved by using color and fill? That seems like a decent option to me. — Jaccar, Feb 13 '19 at 11:47
Please read this [post](https://stackoverflow.com/questions/5963269/how-to-make-a-great-r-reproducible-example) and edit your question accordingly. — NelsonGon, Feb 13 '19 at 11:52
Hope it is the right editing. @Megan It is a bit messy to use "color" and "fill". As Adela shows you have to add size, color ans shape options to get a good job. You may also need another color key...On the other hand the use of addons package is also a bit heavy...Anyway, thanks for your comments. — marc, Feb 14 '19 at 10:42

score 6 · Answer 1 · edited Feb 13 '19 at 12:09

In basic ggplot2 it is impossible if I remember correctly. But this repository may be your answer:

https://github.com/eliocamp/ggnewscale

or this (mentioned in description of the previous one):

https://github.com/clauswilke/relayer

I haven't been using ggplot2 for quite a long time so I'm not familiar with these two, but I remember that I used one of them at least once.

I've just wrote quick example to check if it works:

d1 <- data.frame(x=1:5, y=1)
d2 <- data.frame(x=1:5, y=2)

library(ggplot2)
library(ggnewscale)

ggplot() +
  geom_point(data = d1, aes(x=x, y=y, color = x)) +
  scale_color_continuous(low = "#0000aa", high="#ffffff") +
  new_scale_color() +
  geom_point(data = d2, aes(x=x, y=y, color = x)) +
  scale_color_continuous(low = "#aa0000", high="#00aa00")

example

And it seems to work as you want.

Yes it is exactly what I wanted to achieve ! – marc Feb 13 '19 at 12:34 — marc, Feb 13 '19 at 12:34

score 2 · Answer 2 · answered Feb 13 '19 at 12:03

2

I used your idea about combining col and fill and small hack to use different shapes for cov1 and cov2:

# sample data
my_data <- data.frame(x = 1:5,
                      cov1 = 1:5,
                      cov2 = seq(0.01, 0.05, 0.01))

library(ggplot2)

ggplot() + 
  geom_point(data = my_data, aes(x = x, y = 0.5, col = cov1), shape = 16) +
  scale_color_continuous(low = "red1", high = "red4") + 
  geom_point(data = my_data, aes(x = x, y = -0.5, fill = cov2), shape = 21, col = "white", size = 2) + 
  ylim(-1, 1)

Hope it helps.

answered Feb 13 '19 at 12:03

Adela

1,757
19
37

Yes, thanks. Sometimes it is hard to get a clean solution to simple question in ggplot2. Ok, you can use multiple addon package but it makes it a bit eavy. As a matter of fact I couldnot even get a good solution with fill, mayby because I didnot used the correct shape. Thanks again. – marc Feb 13 '19 at 13:01

Two different color keys in ggplot

2 Answers2