Instructions for R/IDL/Matlab/DS9/etc. users

Would be good to have instructions on how R/IDL/Matlab/etc users might be able to use the cmasher colourmaps. Similarly, for certain application, this might be a good idea as well. Perhaps in the README or in the online documentation.

• R (3ce67f9)
• IDL
• MATLAB
• DS9

[calofost]

I used the R package ‘RColorBrewer’ to load in the RGB colour scales. Installing RColorBrewer is very simple:

#If RColorBrewer is not already install, install it with:
install.packages('RColorBrewer')

Run the following code after you first download CMasher (or after every update) to create an RDS object that may be loaded into any R project. Be sure to edit the colormaps_path to the CMasher-master/cmasher/colormaps folder on your machine and the RDSfilepath to where you’d like to save the RDS object for future use.

#Load CMasher colours - must cite CMasher2020 - (i.e. van der Velden 2020)

#Loading RColorBrewer package.
library(RColorBrewer)

#Edit following paths:
colormaps_path='/path/to/CMasher-master/cmasher/colormaps'
RDSfilepath='/path/to/where/you/wanna/keep/the/RDS/object'

#Looking up the names of the scales and location of the _norm.txt files:
cmr_cmaps_files=list.files(path=colormaps_path, recursive=TRUE, all.files=TRUE, full.name=TRUE, pattern='_norm.txt')
cmr_cmaps_list=list.dirs(path=colormaps_path, full.names=FALSE)
cmr_cmaps_list=cmr_cmaps_list[2:length(cmr_cmaps_list)] #Removing "." from the list of directories.

#Loading all colour scales and adding them to a list object containing all scales called cmr_cmaps..
cmr_cmaps=list()
for (cmr_cmap in cmr_cmaps_list) {
  CM_RGB=read.table(file=cmr_cmaps_files[grep(pattern=cmr_cmap,cmr_cmaps_list)])
  colnames(CM_RGB)=c('R','G','B')
  assign(cmr_cmap, rgb(red=CM_RGB$R, green=CM_RGB$G, blue=CM_RGB$B))
  cmr_cmaps[[cmr_cmap]] = get(cmr_cmap)
}

#Create RDS file containing all CMasher colormaps into a single object:
saveRDS(cmr_cmaps,file=paste0(RDSfilepath, '/', 'cmr_cmaps.RDS'))

Then, when you’re ready to load the CMasher scales again, just skip the above and run the following to get the scales back (be sure to update the RDSfilepath of course):

#Easy to load using the RDS object back into any R project using:
RDSfilepath='/path/to/where/you/wanna/keep/the/RDS/object'
cmr_cmaps=readRDS(file=paste0(RDSfilepath, '/', 'cmr_cmaps.RDS'))

There you go, the colour maps are all contained within the cmr_cmaps R object list. To access a specific colour map, just use the ‘$’ operator : e.g. the rainforest is in cmr_cmaps$rainforest.

Below is an example use:

#Example use (volcano is an example dataset pre-loaded in every R installation):
par(mar=c(4,4,1,0.5))
layout(matrix(c(1,2),1, 2, byrow = TRUE), widths=c(3,1))
image(volcano, col = cmr_cmaps$rainforest, main = "rainforest")
par(mar=c(5,1,5,2.5))
image(y=seq(from=min(volcano),to=max(volcano),by=(diff(range(volcano)))/length(cmr_cmaps$rainforest)),z=t(1:length(cmr_cmaps$rainforest)), col=cmr_cmaps$rainforest, axes=FALSE, main="variable name", cex.main=.8)
axis(4,cex.axis=0.8,mgp=c(0,.5,0))

This is the output plot:

There are many other ways to make colour maps, but these functions are built-into R, so no need to install further packages apart from the RColorBrewer. These should run either in RStudio or on the R command-line. They can be incorporated within scripts easily.

[1313e]

@calofost Thank you very much for the example. I will add it to the documentation as soon as possible.