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
>>
>
