Add coastline to an existing xyplot [SEC=UNCLASSIFIED]

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plot() is a base graphics function. You can not use it in a Lattice
context. And also you can not add to a Lattice plot as you tried to
do: you need to use a panel function, or call trellis.focus(). I
suggest you read the Lattice documentation.

This is one way to do it:

library(sp)

xyplot(lat ~ long, data=mud, panel=function(...) {
sp.polygons(coastline)
panel.xyplot(...)
},
asp="iso", type="p", pch=1, cex=0.01, xlab="", ylab="")
Hi there,

I tried to add a coastline that is imported from a shapefile to a xyplot of
sample points, but I got an error message.

library(lattice)

library(maptools)

xyplot(mud$lat~mud$long, asp="iso", type="p", pch=1, cex=0.01, xlab="",
ylab="")

plot(coastline, add=T)
Error in plot.xy(xy.coords(x, y), type = type, ...) :

        plot.new has not been called yet

I also tried using plot.new=TRUE in the xyplot and got the same message.

I could get a plot from only using plot(coastline),  but could not add it to
the existing xyplot.

Thanks in advance.

Jin

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Felix Andrews / ???
PhD candidate
Integrated Catchment Assessment and Management Centre
The Fenner School of Environment and Society
The Australian National University (Building 48A), ACT 0200
Beijing Bag, Locked Bag 40, Kingston ACT 2604
http://www.neurofractal.org/felix/
3358 543D AAC6 22C2 D336  80D9 360B 72DD 3E4C F5D8
Hi,

You could use the function spplot in the sp-pacakge. Use the sp.layout 
argument to add the shapefile to the plot. All the data needs to be in 
one of the Spatial classes provided by the sp-package. The code could 
look something like:

library(sp)
library(maptools)
points = read.table("points.csv")
coordinates(points) = ~x+y
shape_coast = readShapePoly("coast.shp") # Function from maptools
spplot(points, "attribute1", sp.layout = list("sp.polygons", shape_coast))
?spplot

hth,
Paul
Hi there,
I tried to add a coastline that is imported from a shapefile to a xyplot
of
sample points, but I got an error message.

library(lattice)

library(maptools)

xyplot(mud$lat~mud$long, asp="iso", type="p", pch=1, cex=0.01, xlab="",

ylab="")

plot(coastline, add=T)

Error in plot.xy(xy.coords(x, y), type = type, ...) :
        plot.new has not been called yet

I also tried using plot.new=TRUE in the xyplot and got the same message.

I could get a plot from only using plot(coastline),  but could not add
it to
the existing xyplot.

Thanks in advance.
Jin

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