Order preserving sampling

r-lidar · May 7, 2024 · db82633 · db82633
1 parent 9e05257
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diff --git a/NEWS.md b/NEWS.md
@@ -3,7 +3,7 @@ If you are viewing this file on CRAN, please check [the latest news on GitHub](h
 ## lidR v4.1.2 (Release date: )
 
 - Fix: strongly improved arithmetic accuracy in `point_in_triangle` to improve the quality of delaunay triangulation interpolations and avoid local NAs
-
+- Enhance: `decimate_points()` with `random()` now preserves the point ordering.
 
 ## lidR v4.1.1 (Release date: 2024-02-03)
 

diff --git a/R/algorithm-dec.R b/R/algorithm-dec.R
@@ -48,7 +48,11 @@ random = function(density, use_pulse = FALSE)
     else
     {
       if (nrow(las@data) > n)
-        return(sample(1:nrow(las@data), n))
+      {
+        idx = sample(1:nrow(las@data), n)
+        idx = sort(idx)
+        return(idx)
+      }
       else
         return(1:nrow(las@data))
     }
@@ -237,6 +241,7 @@ random_per_voxel = function(res = 1, n = 1)
 
   selectedPulses <- sample(p, n)
   selectedPulses <- pulseID %in% selectedPulses
+  selectedPulses <- sort(selectedPulses)
 
   return(selectedPulses)
 }