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transparency using plot+points with sp classes

6 messages · David Winsemius, Chris Campbell, Ana +2 more

Ana
#
How can I make one point graphics with transparency

These are all sp classes:

plot(polygons_area,axes=TRUE,asp=1.5,main="Title",xlab="Latitude",
ylab="Longitude")
points(observations2000,type = "p",pch=21,col="green")
points(observation1999,type = "p",pch=21,col="blue")
points(reference.points,type = "p",pch=21,col="red")

how can I add transparency to one of the point graphics, for example
points(observation1999,type = "p",pch=21,col="blue")  ?
#
On Dec 28, 2011, at 7:13 AM, Ana wrote:

            
Read the Details section of :

?rgb
#
# use the alpha argument of rgb or hsv to create transparent colours

require(sp)
xc <- round(runif(20), 2)
yc <- round(runif(20), 2)
xy <- cbind(xc, yc)
xy.sp <- SpatialPoints(xy)

col1 <- hsv(h = (1:10)/80, v = 0.9, alpha = 0.3)
col2 <- hsv(h = 0.25+(1:10)/50, v = 0.8, alpha = 0.4)

plot(xy.sp[1:10,], pch = 21, col = "red", cex = 20, 
  bg = col1)

points(xy.sp[11:20, ], pch = 21, col = "darkgreen", cex = 10, 
  bg = col2)

# Happy Christmas!

Chris Campbell
MANGO SOLUTIONS
Data Analysis that Delivers
+44 1249 767700

-----Original Message-----
From: r-help-bounces at r-project.org [mailto:r-help-bounces at r-project.org] On Behalf Of Ana
Sent: 28 December 2011 12:13
To: r-help at r-project.org
Subject: [R] transparency using plot+points with sp classes

How can I make one point graphics with transparency

These are all sp classes:

plot(polygons_area,axes=TRUE,asp=1.5,main="Title",xlab="Latitude",
ylab="Longitude")
points(observations2000,type = "p",pch=21,col="green") points(observation1999,type = "p",pch=21,col="blue") points(reference.points,type = "p",pch=21,col="red")

how can I add transparency to one of the point graphics, for example points(observation1999,type = "p",pch=21,col="blue")  ?

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Ana
#
Hi guys,
Thansk for the help with the transparency.

I've made some modifications to my code , added rgb in colour to play
with the transparency and included also a north arrow. I was trying to
make the code look better, however i am facing another problem, once I
use symbols with a bg colour. Somehow once I plot the map I loose the
bg colour info and he gives me only the filled triangle border colour:

arrow <- list("SpatialPolygonsRescale", layout.north.arrow(type=1),
offset = c(5,10), scale = 2,col="black")

list1=list("sp.points",observations2000,pch=21,col = rgb(red = 0,
green = 0, blue = 1, alpha = 0.1))

list2=list("sp.points,"observations1999,pch=21,col="blue")

list3=list("sp.points",reference.points,pch=24,col="red",bg="orange")

spplot(polygon_area,"NAME",col="black",col.regions=FALSE, colorkey=FALSE,

       sp.layout=list(arrow,list1,list2,list3),

       scales=list(draw=TRUE),xlab="Longitude",ylab="Latitude", main="Map" )
On Wed, Dec 28, 2011 at 1:13 PM, Ana <rrasterr at gmail.com> wrote:
#
Some output devices don't support transparency. Try a different output device.
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Ana <rrasterr at gmail.com> wrote:

            
#
This code is not reproducible, hence hard to know if there is a problem 
with R, a contributed package, or what you wrote or did.

Best,
Uwe Ligges
On 28.12.2011 18:07, Ana wrote: