Legend in density plot
On 18/11/11 21:13, Albin Blaschka wrote:
Dear list!
I have GPS data for three seasons of roaming livestock and to get an
idea which areas the animals occupied and the differences between the
seasons, I am plotting density plots for each season like this:
posi <- readOGR(dsn = "PG:host=127.0.0.1 user=user dbname=mydb
password=secret, layer = "mylayer")
pposi <- ppp(posi at coords[,1],
posi at coords[,2],xrange=c(posi at bbox[1,1],posi at bbox[1,2]),
yrange=c(posi at bbox[2,1],posi at bbox[2,2]))
densi <- density(pposi, bw = "nrd0", adjust = 0.1, kernel =
c("epanechnikov"), edge = TRUE, diggle=TRUE)
plot(densi, col = mypalette)
so far, so good:
BUT as there where differences between the years, the legend which is
plotted on the left of each map shows different values/ has different
ranges, which is bad for a comparision, so my question is:
How can I change the range and the ticks in the legend of a density map?
I hope I made my point clear - Thank you in advance!
I ***think*** when you say ``legend'' you mean the ***ribbon*** that
appears at
the right hand side of an "im" plot. And I ***think*** you want this
ribbon to cover
the same range of values for each plot.
This is easily done --- choose the range of values that you want to use,
and invoke
the argument "zlim".
Here's a toy example:
X <- im(matrix(runif(10000),100,100))
Y <- im(matrix(runif(10000,0.5,1.5),100,100))
plot(X) # No adjustment --- the two images look pretty much the same;
plot(Y) # you can't see the difference in the ranges of values.
plot(X,zlim=c(0,1.5))
plot(Y,zlim=c(0,1.5)) # Now the difference is obvious.
I hope I have interpreted your question correctly. If not, please let me
know, with clarifications.
cheers,
Rolf Turner