On 01/31/2014 08:58 PM, 李德磊 wrote: > Hello everyone, > I have no idea how to plotting points over a map using R, in which the colors > of the points stand for the points' value. I'd like to get a map as shown in > attachment picture which was plotted using matlab. Does anyone know how to do > it using R? Thank you very much for your help in advance. > Kind regards,Dli
Hi Dli, Your question involves two things, the placement of the points and their color. The coordinate system of maps is almost always geographic, in decimal degrees. The x values are the longitudes measured from the prime meridian that passes through Greenwich, England. The y values are the latitudes that are measured from the equator. To get the colors for the points, if you have some value like average temperature for the points, you can convert the numbers into colors using functions like color.scale in the plotrix package. The resulting vector or matrix of colors can then be passed to the "points" function. Jim ______________________________________________ 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.
