I want to fill the area under curve with the optical spectrum colors, getting a plot like this.
This is what I tried
ggplot(bq, aes(x=w.length, y=s.e.irrad))
geom_segment(aes(xend=w.length, yend=0, colour=abs(w.length)^0.7*sign(w.length)))
geom_line()
scale_colour_gradient2(low=scales::muted("blue"),
mid=scales::muted("green"),
high=scales::muted("red"))
getting this
Also tried with geom_area
ggplot(bq, aes(x = w.length, y = s.e.irrad))
geom_area(fill = "steelblue") #steelblue is for example
But can't fill with gradient
My dataframe has wavelengths in x and Irradiance in y
CodePudding user response:
The following should be close to what you're looking for. The trick is to use scale_color_identity
for the geom_segment
, and passing to the color aesthetic an RGB string that represents each wavelength in your data frame.
ggplot(bq, aes(x=w.length, y=s.e.irrad))
geom_segment(aes(xend=w.length, yend=0, colour = nm_to_RGB(w.length)),
size = 1)
geom_line()
scale_colour_identity()
Or if you want a more muted appearance:
ggplot(bq, aes(x=w.length, y=s.e.irrad))
geom_area(fill = "black")
geom_segment(aes(xend=w.length, yend=0,
colour = nm_to_RGB(w.length)),
size = 1, alpha = 0.3)
geom_line()
scale_colour_identity()
The only drawback being that you need to define nm_to_RGB
: the function that converts a wavelength of light into a hex-string to represent a color. I'm not sure there's a "right" way to do this, but one possible implementation (that I translated from the javascript function here) would be:
nm_to_RGB <- function(wavelengths){
sapply(wavelengths, function(wavelength) {
red <- green <- blue <- 0
if((wavelength >= 380) & (wavelength < 440)){
red <- -(wavelength - 440) / (440 - 380)
blue <- 1
}else if((wavelength >= 440) & (wavelength<490)){
green <- (wavelength - 440) / (490 - 440)
blue <- 1
}else if((wavelength >= 490) && (wavelength<510)){
green <- 1
blue = -(wavelength - 510) / (510 - 490)
}else if((wavelength >= 510) && (wavelength<580)){
red = (wavelength - 510) / (580 - 510)
green <- 1
}else if((wavelength >= 580) && (wavelength<645)){
red = 1
green <- -(wavelength - 645) / (645 - 580)
}else if((wavelength >= 645) && (wavelength<781)){
red = 1
}
if((wavelength >= 380) && (wavelength<420)){
fac <- 0.3 0.7*(wavelength - 380) / (420 - 380)
}else if((wavelength >= 420) && (wavelength<701)){
fac <- 1
}else if((wavelength >= 701) && (wavelength<781)){
fac <- 0.3 0.7*(780 - wavelength) / (780 - 700)
}else{
fac <- 0
}
do.call(rgb, as.list((c(red, green, blue) * fac)^0.8))
})
}
Obviously, I don't have your data set, but the following code creates a plausible set of data over the correct ranges:
Data
set.seed(10)
bq <- setNames(as.data.frame(density(sample(rnorm(5, 600, 120)))[c("x", "y")]),
c("w.length", "s.e.irrad"))
bq$s.e.irrad <- bq$s.e.irrad * 1e5