You may be looking for the par settings of xaxs="i", yaxs="i", which if you add them to the plot call will prevent the "regular" behavior of adding 4% padding to the axis widths.
?par
-- David.
On May 18, 2011, at 8:27 AM, Pierre Bruyer wrote:
I've pratically resolved my problem (the code is under that), but a last thing is not perfect:
when I use the function plot to call after the function polygon, there is a marge between my raster and the window. I think it's the axis of the function "plot()", but I have not found how delete it. Someone have a solution please?
Pierre Bruyer
##smooth contour
contours <- contourLines(V2b,levels=paliers)
par(mar=c(0,0,0,0))
plot(1,col="white",main="polygon()", asp = 1, axes = FALSE, ann = FALSE,xlim=c(0,1), ylim = c(0,1),type = "n", method = c("image"))
for (i in seq_along(contours)) {
x <- contours[[i]]$x
y <- contours[[i]]$y
c <- contours[[i]]$level
j <- 1
tmp <- 0
while(j < length(level[,1]) && tmp == 0){
if(level[j,1] == c){
tmp <- j
}
j <- j+1
}
polygon( spline( seq_along(x), x)$y, spline( seq_along(y), y)$y ,col = colgraph[tmp+1], border = NA)
}
Le 17 mai 2011 ? 16:44, Pierre Bruyer a ?crit :
The result is good, thanks a lot, but how can I with this method fill my raster to color?
Le 17 mai 2011 ? 15:43, Duncan Murdoch a ?crit :
I don't think filled.contour gives you access to the contour lines. If you use contourLines() to compute them, then you can draw them using code like this:
contours <- contourLines(V2b,levels=paliers)
for (i in seq_along(contours)) {
x <- contours[[i]]$x
y <- contours[[i]]$y
lines( splines( seq_along(x), x)$y, splines( seq_along(y), y)$y )
}
but as I said, you won't get great results. A better way is to use a finer grid, e.g. by fitting a smooth surface to your set of points and using predictions from the model to interpolate.
Duncan Murdoch
On 17/05/2011 9:35 AM, Pierre Bruyer wrote:
I work with large datasets (10000 points) so I can't post them , but my function is :
create_map<- function(grd, level ,map_output, format = c("jpeg"), width_map = 150, height_map = 150,...)
{
##sp<- spline(x = grd[,1], y = grd[,2])
grd2<- matrix(grd[,3], nrow = sqrt(length(grd[,3])), ncol = sqrt(length(grd[,3])), byrow = FALSE)
V2b<- grd2
##creation of breaks for colors
i<-1
paliers<- c(-1.0E300)
while(i<=length(level[,1]))
{
paliers<- c(paliers,level[i,1])
i<- i+1
}
paliers<- c(paliers, 1.0E300)
##scale color creation
i<- 1
colgraph<- c(rgb(255,255,255, maxColorValue = 255))
while(i<=length(level[,2]))
{
colgraph<- c(colgraph, rgb(level[i,2],level[i,3],level[i,4], maxColorValue = 255))
i<- i +1
}
##user can choose the output format (default is jpeg)
switch(format,
png = png(map_output, width = width_map, height = height_map) ,
jpeg = jpeg(map_output, width = width_map, height = height_map, quality = 100),
bmp = bmp(map_output, width = width_map, height = height_map),
tiff = tiff(map_output, width = width_map, height = height_map),
jpeg(map_output, width = width_map, height = height_map))
## drawing map
##delete marge
par(mar=c(0,0,0,0))
filled.contour(V2b, col = colgraph, levels = paliers, asp = 1, axes = FALSE, ann = FALSE)
dev.off()
}
where grd is a xyz data frame,
map_output is the path+name of the output image file,
and level is a matrix like this :
level<- matrix(0,10,4)
level[1,1]<- 1.0000E+00
level[2,1]<- 3.0000E+00
level[3,1]<- 5.0000E+00
level[4,1]<- 1.0000E+01
level[5,1]<- 1.5000E+01
level[6,1]<- 2.0000E+01
level[7,1]<- 3.0000E+01
level[8,1]<- 4.0000E+01
level[9,1]<- 5.0000E+01
level[10,1]<- 7.5000E+01
level[1,2]<- 102
level[2,2]<- 102
level[3,2]<- 102
level[4,2]<- 93
level[5,2]<- 204
level[6,2]<- 248
level[7,2]<- 241
level[8,2]<- 239
level[9,2]<- 224
level[10,2]<- 153
level[1,3]<- 153
level[2,3]<- 204
level[3,3]<- 204
level[4,3]<- 241
level[5,3]<- 255
level[6,3]<- 243
level[7,3]<- 189
level[8,3]<- 126
level[9,3]<- 14
level[10,3]<- 0
level[1,4]<- 153
level[2,4]<- 204
level[3,4]<- 153
level[4,4]<- 107
level[5,4]<- 102
level[6,4]<- 33
level[7,4]<- 59
level[8,4]<- 63
level[9,4]<- 14
level[10,4]<- 51
Le 17 mai 2011 ? 15:17, Duncan Murdoch a ?crit :
On 17/05/2011 8:24 AM, Pierre Bruyer wrote:
Thank you for your answer, but the function spline() (and a lot of other function in R) can't take in its parameters the original contour which are define by a vector, i.e. :
If you post some reproducible code to generate the contours, someone will show you how to use splines to interpolate them.
Duncan Murdoch
##creation of breaks for colors
i<-1
paliers<- c(-1.0E300)
while(i<=length(level[,1]))
{
paliers<- c(paliers,level[i,1])
i<- i+1
}
paliers<- c(paliers, 1.0E300)
Le 17 mai 2011 ? 13:05, Duncan Murdoch a ?crit :
On 11-05-17 5:58 AM, Pierre Bruyer wrote:
I'm a French developer (so I am sorry if my english is not perfect). I have a problem to smooth the contours of a map. I have a dataset with 3 columns, x, y and z, where x and y are the coordinates of my points and z is evaluate to a qualitative elevation and his representation is a set of colors, which is define by levels.
The problem is the curve of my contour is so linear, and I would like a more continuous contour. I use the function fitted.contour to draw my map.
If you use a finer grid of x,y values you'll get shorter segments and they will look smoother.
You might be able to use a smooth interpolator (e.g. spline()) rather than linear interpolation, but those occasionally do strange things e.g.
x<- c(1:4, 5.9, 6:10)
y<- c(1:4, 7, 6:10)
plot(spline(x,y, n=200), type="l")
points(x,y)
where one point is out of line with the others, but the curve overcompensates in order to stay smooth.
Duncan Murdoch