On Tue, Nov 26, 2013 at 9:58 AM, Prof Brian Ripley <rip...@stats.ox.ac.uk> wrote:
>> But the image function (and probably levelplot) doesn't allow that so > > Mis-information alert! The help says > > col: a list of colors such as that generated by ‘rainbow’, > ‘heat.colors’, ‘topo.colors’, ‘terrain.colors’ or similar > functions. > > and look at what they generate. Or see e.g. ?col2rgb . > > Although base graphics has the concept of a palette of colours, AFAIK it > has always been bolted on top of a general colour specification, > originally RGB and for many years already RGBA. Yes image allows you to specify col=, but it always specifies a palette. The matrix values are scaled from 1:length(col) and looked up in that palette. You can't call image with z as matrix of colours and get those colours, nor set col to a matrix of colours and a see those colours laid out. This is unlike points() where specifying col= as a vector of the same length as the number of points gives you a 1:1 mapping of points to colours. To do image() with a 1:1 mapping of cell values to colours requires a tiny bit of hoop-jumping. Barry ______________________________________________ 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.
