Michael Sumner wrote:
Here's one way. I'm not sure about how to control the aspect ratio
(something I've been meaning to check for a while now).
somewhat of a non-newby answer to Michael: asp is set in plot.Spatial,
and if the default value of NA is passed, set to:
if (is.na(asp)) asp <- ifelse(is.na(proj4string(x)) || is.projected(x),
1.0, 1/cos((mean(ylim) * pi)/180))
i.e. 1.0, or a somewhat more sensible value for longlat data.
if you override the NA default with "", asp is taken from the device
geometry -- the plot fills the device. For geographic data this usually
means arbitrary stretching in some direction.
library(sp)
data(volcano)
x <- 10*(1:nrow(volcano))
y <- 10*(1:ncol(volcano))
## image xyz list
imlist <- list(x = x, y = y, z = volcano)
## SpatialGridDataFrame (image2Grid is v. simple, see definition)
imspdf <- image2Grid(imlist)
image(imspdf, col = terrain.colors(100),axes = FALSE, asp = "")
contour(imspdf, levels = seq(90, 200, by=5),add = TRUE, col ="peru")
axis(1, at = seq(100, 800, by = 100))
axis(2, at = seq(100, 600, by = 100))
box()
title(main = "Maunga Whau Volcano",font.main = 4)
On Tue, Jan 5, 2010 at 1:34 PM, Jason Rupert <jasonkrup...@yahoo.com> wrote:
At the suggestion of Walmes Zeviani I downloaded and am taking a look at the sp
package.
In an attempt to get going, can someone offer a suggestion about how to convert
the below over to a version that uses the sp package?
data(volcano)
x <- 10*(1:nrow(volcano))
y <- 10*(1:ncol(volcano))
image(x, y, volcano,col = terrain.colors(100),axes = FALSE)
contour(x, y, volcano, levels = seq(90, 200, by=5),add = TRUE, col ="peru")
axis(1, at = seq(100, 800, by = 100))
axis(2, at = seq(100, 600, by = 100))
box()
title(main = "Maunga Whau Volcano",font.main = 4)
Thanks for any feedback and insights.
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--
Edzer Pebesma
Institute for Geoinformatics (ifgi), University of Münster
Weseler Straße 253, 48151 Münster, Germany. Phone: +49 251
8333081, Fax: +49 251 8339763 http://ifgi.uni-muenster.de
http://www.52north.org/geostatistics e.pebe...@wwu.de
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