CODEWITHSUNDEEP
rggplot2colorsalphapalette
fede_luppi
fede_luppi

Reputation: 1171

Set transparency/saturation of palette in ggplot

Let's start with the viridis palette. In my opinion, colours are a bit just too bright for me, and for my purposes they look too artificial. therefore, I would like to apply some sort of transparency or similar to reduce saturation:

library(nord)
library(scales)
library(viridis)
library(nord)

show_col(viridis(5))
show_col(viridis(5, alpha=.5))

Applying alpha transparency internally seems to work. enter image description here.

However, when run in ggplot, it automatically changes alpha to 1 and plots the original viridis in full intensity:

ggplot(faithfuld, aes(waiting, eruptions)) +
  geom_raster(aes(fill = density)) +
  scale_fill_viridis(5, alpha=.5)

enter image description here

In another example, I found the opposite problem, lack of intensity/saturation. For example, the "aurora" palette from the nord package is great, but it looks a bit faded, lacking some saturation, at least for my purposes.

show_col(nord("aurora",5))

enter image description here

Similarly, I tried to set alpha internally, in this case to 1, but this pruduces a different effect as compared to viridis, changing the palette.

show_col(nord("aurora", alpha=.5))

enter image description here
Alternatively, I have set alpha as alpha(). However, this only changes the color names, but they look the same.

show_col(alpha(nord("aurora",5)), .5)

enter image description here

How can I reduce saturation/intensity in viridisand increase in the nord palettes in ggplot?

Upvotes: 9

Views: 6534

Answers (3)

eipi10
eipi10

Reputation: 93811

You can adjust the viridis colors to reduce their saturation without making them transparent. I was hoping you could do this within the viridis function, but it doesn't look like there's a way to do that. Instead, the example below is a function that converts a vector of hexadecimal input colors (we'll create this vector with the viridis function) to the hsv colorspace, adjusts the saturation and value levels and then converts back to hexadecimal.

The approach below is a bit convoluted. There are probably more direct ways to transform between color systems.

vir_lite = function(cols, ds=0.4, dv=0.7) {
  cols = rgb2hsv(col2rgb(cols))
  cols["v", ] = cols["v", ] + dv*(1 - cols["v", ])
  cols["s", ] = ds*cols["s", ]
  apply(cols, 2, function(x) hsv(x[1], x[2], x[3]))
}

Here are the original viridis colors:

show_col(viridis(5))

enter image description here

And the adjusted colors:

show_col(vir_lite(viridis(5)))

enter image description here

You can change the adjusted colors by changing the ds and dv arguments. Now let's use the adjusted colors in the plot:

p = ggplot(faithfuld, aes(waiting, eruptions)) +
      geom_raster(aes(fill = density))

p + scale_fill_gradientn(colors=vir_lite(viridis(5)))

enter image description here

p + scale_fill_gradientn(colors=vir_lite(viridis(5), ds=0.6, dv=0.5))

enter image description here

Upvotes: 8

drmariod
drmariod

Reputation: 11762

You have a little typo in your last function. the .5 is within show_col and not within alpha. So within show_col it gets interpret as a rounded 1 and this is boolean TRUE which leads to show the HEX values.

So the correct line would be

show_col(alpha(nord("aurora",5), .5))

And this produces the faint colors.

Upvotes: 1

De Novo
De Novo

Reputation: 7610

Add your alpha value to the geom_raster() layer:

ggplot(faithfuld, aes(waiting, eruptions)) +
    geom_raster(alpha = 0.5, aes(fill = density)) +
    scale_fill_viridis(5)

enter image description here

Upvotes: 5

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