st_thintrack: Thin a track just keeping the points separated by a user...

In pgirmess: Spatial Analysis and Data Mining for Field Ecologists

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)

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...

Value

A sf POINT object of the track thinned.

See Also

mergeTrackObs

Examples

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)

}

pgirmess documentation built on April 8, 2023, 1:12 a.m.