hadley wickham <[EMAIL PROTECTED]> wrote: > You might be able to do this with the ggplot2 package - see for > example http://had.co.nz/ggplot2/coord_map.html, which shows plots on > map coordinate systems. Because the design of ggplot2 means the > coordinate system and geom (eg. points vs tiles) operate > independently, you can draw image plots > (http://had.co.nz/ggplot2/geom_tile.html) in any coordinate system.
These aren't quite what I have in mind. > Can you provide more details about your curvilinear coordinate system? The idea is that you're modeling an irregular shaped object, a body of water, a river or estuary, say. It's fairly common practice to use a grid squished and rotated so that the main flow is along one axis, and the other axis spans the flow in most spots. So there is a single transformation that gets you from a rectangular grid to the shape of your estuary, but there isn't a tidy analytical way to describe it, like there is with a map projection. Instead there is an x and y for each grid point, and the cell dimensions vary all over the place. spplot, in the sp package seems almost to do what I'm after, but I can't figure out if there is a way to invoke it that does what I want, or if I'm barking up the wrong tree. Thanks, -tom > > On 9/26/07, Tom Sgouros <[EMAIL PROTECTED]> wrote: > > > > Hello all: > > > > A question from a new user. I have data on a geo-referenced curvilinear > > grid. This is a grid with 75 rows and 51 columns, is not aligned > > north-south, and the rows and columns are not straight. (And the > > coordinates are in meters.) I want to make image plots of this data, > > but where the grid is deformed according to the correct locations of the > > grid points, instead of coming out rectangular. > > > > I've found the sp package, which seems to be kind of close to what I'm > > after, but maybe I haven't figured out how to invoke it properly, or > > maybe there's another package I haven't found yet. Can anyone direct me > > to how to use R to map this kind of data? Is there an example someone > > might be able to share with me? > > > > Is there a collection of plots somewhere that someone might browse to > > answer questions like this? > > > > Many thanks, > > > > -tom > > > > -- > > ------------------------ > > tomfool at as220 dot org > > http://sgouros.com > > http://whatcheer.net > > > > ______________________________________________ > > 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. > > > > > -- > http://had.co.nz/ > -- ------------------------ tomfool at as220 dot org http://sgouros.com http://whatcheer.net ______________________________________________ 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.
