st_thintrack: Thin a track just keeping the points separated by a user defined minimal distance

Description

Thin a track stored as a sf POINT object, just keeping the points separated by a user defined minimal distance.

Usage

st_thintrack(spdf,mindist=100)

Value

A sf POINT object of the track thinned.

Arguments

spdf: a sf of POINT tracks
mindist: minimal distance requested between two points (default = 100)

Details

Tracks downloaded from GPS often provide an unnecessary large density of points at irregular distances. This function starts reading from the first point of the track and removes all points within a user specified radius (USR), then reads the next point and removes all points within the USR, and so on...

Examples

Run this code


if(require(sf)){

mySPDF<-structure(list(x = c(748775, 748807, 748834, 748854, 748871, 
748873, 748880, 748910, 748919, 748917, 748921, 748923, 748924, 
748921, 748921, 748921, 748922, 748915, 748616, 748613, 748612, 
748613, 748613, 748615, 748613, 748616, 748615, 748618, 748615, 
748619, 748618, 748620, 748586, 748553, 748494, 748444, 748424, 
748366, 748305, 748305), y = c(105716, 105761, 105808, 105856, 
105911, 105964, 106019, 106065, 106114, 106167, 106219, 106274, 
106329, 106385, 106441, 106494, 106550, 106571, 105835, 105779, 
105723, 105665, 105600, 105537, 105473, 105412, 105350, 105293, 
105234, 105180, 105123, 105070, 105023, 104960, 104956, 104947, 
104906, 104905, 104901, 104904), ID = 1:40), .Names = c("x", 
"y", "ID"), row.names = c("1", "2", "3", "4", "5", "6", "7", 
"8", "9", "10", "11", "12", "13", "14", "15", "16", "17", "18", 
"19", "20", "21", "22", "23", "24", "25", "26", "27", "28", "29", 
"30", "31", "32", "33", "34", "35", "36", "37", "38", "39", "40"
), class = "data.frame")

mySPDF<-st_as_sf(mySPDF,coords=c("x","y"))

plot(st_geometry(mySPDF),pch=19,cex=0.5)
plot(st_thintrack(mySPDF),pch=19,cex=0.7,col="red",add=TRUE)

plot(mySPDF,pch=19,cex=0.5)
plot(st_thintrack(mySPDF,min=200),pch=19,cex=0.7,col="red",add=TRUE)

}