The goal of colorplane
is to facilitate the creation and manipulation
of color maps that can be rescaled, thresholded, and blended. The main
motivation for the package was to help with the creation of image
overlays for the display of scalar fields on a backgroound image
(e.g. for display of brain activation maps).
You can install the development version of colorplane from GitHub with:
# install.packages("devtools")
devtools::install_github("bbuchsbaum/colorplane")
We create two color planes that map from “intensity” to colors provided in a color map.
library(colorplane)
vals <- rnorm(100)
cmap <- IntensityColorPlane(vals, cols=rainbow(100))
## now we map to a set of colors, such that the color scale ranges from -1 to 1.
hexmap <- map_colors(cmap, irange=c(-1,1))
print(class(hexmap))
#> [1] "HexColorPlane"
#> attr(,"package")
#> [1] "colorplane"
plot(vals, col=hexmap@clr)
## let's do the same except threshold colors in the range [-.5,.5]
cmap2 <- map_colors(cmap, irange=c(-1,1), threshold=c(-.5,.5))
## cmap2 is an RGBColorPlane because we added element-wise transparency due to thresholding.
## We can convert back to hexcolors to plot.
print(class(cmap2))
#> [1] "RGBColorPlane"
#> attr(,"package")
#> [1] "colorplane"
## Note value between [-.5,.5] are now invisible.
plot(vals, col=as_hexcol(cmap2))
We can also blend colors using alpha composition. Here we simply give all colors a greenish tint to demonstrate color blending.
library(colorplane)
vals <- rnorm(100)
bottom <- map_colors(IntensityColorPlane(vals, cols=rainbow(100)),irange=c(-1,1))
top <- ConstantColorPlane("#00FF00")
blend <- blend_colors(bottom, top, alpha=.5)
plot(vals, col=as_hexcol(blend))
Add the following code to your website.
For more information on customizing the embed code, read Embedding Snippets.