flightpathr

commit ed5b9602c10cfe5dcf4f024d2571a40c55d483d9
parent aefcef6a6a424bc893a967faeee9d463137ec3be
Author: eamoncaddigan <eamon.caddigan@gmail.com>
Date:   Mon, 16 May 2016 10:51:10 -0400

Don't trust bearings for points within 1 mm.

Diffstat:
M
R/coordsToBearing.R
 | 
7
+++++++
M
tests/testthat/test_coordsToBearing.R
 | 
8
++++++++

2 files changed, 15 insertions(+), 0 deletions(-)
diff --git a/R/coordsToBearing.R b/R/coordsToBearing.R
@@ -16,5 +16,12 @@ coordsToBearing <- function(trajectory) {
 
   bearings <- geosphere::bearing(trajectoryCoords[1:(numPoints-1), 1:2],
                                  trajectoryCoords[2:numPoints, 1:2])
+
+  # If successive points have the SAME lon/lat, geosphere::bearing() produces
+  # meaningless output. Set these to NAs.
+  distancesMeters <- geosphere::distHaversine(trajectoryCoords[1:(numPoints-1), 1:2],
+                                              trajectoryCoords[2:numPoints, 1:2])
+  bearings[distancesMeters < 1e-4] <- NA
+
   return(c(bearings, NA))
 }
diff --git a/tests/testthat/test_coordsToBearing.R b/tests/testthat/test_coordsToBearing.R
@@ -40,3 +40,11 @@ test_that("Trajectories are somewhat reversable", {
 
   expect_equal(destPoints[1:200], trajectory[1:200], tolerance = 1e-8)
 })
+
+test_that("Repeated long/lats are handled correctly", {
+  trajectory <- geosphere::gcIntermediate(c(-119.841499, 34.426194),
+                                          c(-74.577166, 39.457583),
+                                          100)
+  trajectory <- rbind(trajectory, trajectory[100, ], trajectory[100, ])
+  expect_true(all(is.na(coordsToBearing(trajectory)[c(100, 101)])))
+})