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 à 15:17, Duncan Murdoch a écrit :
> 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 à 13:05, Duncan Murdoch a écrit :
>>
>> > 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
>>
>
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