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

Description

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

Usage

thintrack(spdf,mindist=100)

Arguments

spdf

a SpatialPointsDataFrame of point tracks

mindist

minimal distance requested between two points (default = 100)

Value

A SpatialPoints object of the track thinned.

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

# NOT RUN {
library(sp)
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")
coordinates(mySPDF)<-~x+y

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

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

# }