CODEWITHSUNDEEP
rggplot2
hardmooth
hardmooth

Reputation: 1262

Colour gradient line as axis

How can I get a line with colour gradient (preferably with multiple stops) as an (y)-axis in ggplot?

I want to add this as a colour-coded evaluation hint to a violin plot. 'Good' will be encoded as green, whereas 'bad' should be red.

What I've come up with was to add an geom_segment to the side, but this doesn't yet work:


R code:

# create some test data
type_list <- c("first", "second", "third")
test_data <- data.frame()

N <- 16
for( i in 1:length(type_list))
{
    test_data = rbind( test_data,
                       data.frame(
                           idx  = 1:N,
                           vals = runif( n = N, min = 0, max = 1),
                           type = type_list[i]
                       )
   )
}

# plot data as violin 
ggplot( test_data, aes( y = vals, fill = type)) +
    geom_violin( aes( x = type )) +
    geom_segment( aes(x = 0, xend = 0, y = 0, yend = 1, color = vals, size = 2))+
    scale_colour_gradientn( colours = c( "darkred", "yellow", "darkgreen"),
                            breaks  = c( 0, 0.5, 1),
                            labels  = c( "bad", "medium", "good"),
                            limits  = c( 0,1)) + 
    guides( size = FALSE, colour = guide_legend( title="Evaluation", reverse = TRUE, 
                                                 override.aes = list( size = 5)))

enter image description here

Upvotes: 2

Views: 1085

Answers (1)

Pigeon
Pigeon

Reputation: 423

geom_segment dosen't work here

ggplot( test_data, aes( y = vals)) +
  geom_violin( aes( x = type, fill = type )) +
  geom_line(data = data.frame(x = c(rep(0,100)), y = seq(0,1,length.out=100)), aes(x=x, y=y, color=y),size=2)+
  scale_colour_gradientn( colours = c( "darkred", "yellow", "darkgreen"),
                          breaks  = c( 0, 0.5, 1),
                          labels  = c( "bad", "medium", "good"),
                          limits  = c( 0,1)) + 
  guides( size = FALSE, colour = guide_legend( title="Evaluation", reverse = TRUE, 
                                               override.aes = list( size = 5)))

enter image description here

Upvotes: 5

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