visualize a list of colors/palette in R

Question

I have following data.frame with rgb values. Hence each row indicates a color.

pdf <- read.table(header = TRUE, text = "
r     g     b
0.374 0.183 0.528
0.374 0.905 0.337
0.051 0.662 0.028
0.096 0.706 0.898
0.876 0.461 0.628
0.415 0.845 0.286
0.596 0.07  0.523
0.724 0.101 0.673
0.847 0.434 0.937
0.588 0.885 0.604
0.481 0.366 0.337
0.142 0.075 0.276
0.819 0.737 0.658
0.91  0.722 0.979
0.969 0.012 0.451
0.887 0.536 0.123
0.432 0.967 0.446
0.927 0.125 0.332
0.381 0.646 0.656
0.04  0.898 0.798
")

How can I visualize these colors? This can be either as bars of color or a palette or a pie chart. I tried to use following method but could not fit it in my data:

pie(rep(1,20), col=rainbow(20)) 

Nidifugous

Answer 1

image() will work well here if you convert the colors via rgb()

image(1:nrow(ddf), 1, as.matrix(1:nrow(ddf)), 
      col=rgb(ddf$r, ddf$g, ddf$b),
      xlab="", ylab = "", xaxt = "n", yaxt = "n", bty = "n")

Wickman

This is exactly what I wanted. – Nidifugous

Answer 2

I think the simplest option is scales. This also has the advantage of showing the hex values in the colours.

library(scales)
pal <- rgb(ddf$r, ddf$g, ddf$b)
show_col(pal)

Kiri

Answer 3

As an alternative to the solution using image you could also use polygon and create a quite similar plot:

plot(NA, xlim=c(0, nrow(ddf)), ylim=c(0,1))

for (i in 1:nrow(ddf)) {

  row <- ddf[i,]
  color <- rgb(red=row$r, green=row$g, blue=row$b)
  polygon(x=c(i-1, i, i, i-1), y=c(0, 0, 1, 1), col = color)
}

Nissie

Good alternative method. Polygon() is a useful function. – Nidifugous

Answer 4

You could also use ggplot2:

library(ggplot2)
qplot(x=1:nrow(ddf), y = 1, fill=factor(1:nrow(ddf)), geom="tile") +
  scale_fill_manual(values = rgb(ddf$r, ddf$g, ddf$b)) +
  theme_void()+
  theme(legend.position="none") 

Henceforward

Good suggestion. – Nidifugous

Answer 5

You can use the hues package:

library("hues")

pal <- c("#351d34", "#f5ccb5", "#159ea2", "#d05d6c", "#ec4934")

swatch(pal)

Teodorateodorico

Seems a new package. I had asked this question 9 years back! – Nidifugous

hahaha I haven't noticed it. But it works pretty good in 2023 :) – Teodorateodorico

Answer 6

Convert to R color with rgb(), plot with ggplot using geom_tile (extending the answer from @Matifou), and add text label.

With the original post data:

    # a palette is a named vector
    myPalette=rgb(pdf)
    names(myPalette) = paste("row", 1:nrow(pdf))
    
    # create data that references the palette
    colorKey = data.frame(colorName=names(myPalette))
    # plot with ggplot, referencing the palette
    ggplot(data=colorKey, aes(x=1, y = 1:nrow(colorKey), fill=colorName, label=colorName)) +
      geom_tile() +
      scale_fill_manual(values = myPalette) +
      theme_void()+
      theme(legend.position="none") + 
      geom_text()

SECOND EXAMPLE - for text labels

    myPalette =  c(
      buttercup = "#6AD749",
      bubbles = "#18B4E5",
      blossum = "#DF76A0")
    
    colorKey = data.frame(colorName=names(myPalette))
    ggplot(data=colorKey, aes(x=1, y = 1:nrow(colorKey), fill=colorName, label=colorName)) +
      geom_tile() +
      scale_fill_manual(values = myPalette) +
      theme_void()+
      theme(legend.position="none") + 
      geom_text()

Quadruplex