Dear list members I'm currently working on some topographic (elevation) data, and was somewhat surprised that the 'topo.colors' and 'terrain.colors' are of little to no use here.
The problem is that these functions only return a palette of colours; they don't map depth values to colours. So if I plot (using 'image', 'persp' or similar functions) and specify these palettes, ocean areas may coloured green (indicating) land, which may be quite confusing. I have looked through various packages, and have found several colour palette functions, but none that do what I need. Basically, I just need a function that takes a vector of elevation values as input, and outputs a vector of 'natural' colours. For negative values (i.e., ocean), the 'blue' colours of 'topo.colors' would be OK, and for positive values either the colours of 'terrain.colors' or the non-blue colours of 'topo.colors' would look nice. It is of course not very difficult to create such a function myself, e.g. using the 'cut' function and a standard palette. But perhaps somebody has already has made one? My ideal topographic colour mapping function would support separate colour levels for water and land (so that you can specifiy for example 5 colours of water, from a depth of 5000 meters to 0 meters, and 20 colours of land, from a depth of 0 meters to 2000 meters), support several nice palettes, and also support logarithmic colour mapping. But I would be happy with a simple one, that just mapped negative values to water colours and positive values to land colours. -- Karl Ove Hufthammer ______________________________________________ R-help@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-help PLEASE do read the posting guide http://www.R-project.org/posting-guide.html and provide commented, minimal, self-contained, reproducible code.
