# trackDistance: Determine distances along a track In trip: Tracking Data

 trackDistance R Documentation

## Determine distances along a track

### Description

Calculate the distances between subsequent 2-D coordinates using Euclidean or Great Circle distance (WGS84 ellipsoid) methods.

### Usage

``````trackDistance(x1, y1, x2, y2, longlat = TRUE, prev = FALSE)
``````

### Arguments

 `x1` trip object, matrix of 2-columns, with x/y coordinates OR a vector of x start coordinates `y1` vector of y start coordinates, if x1 is not a matrix `x2` vector of x end coordinates, if x1 is not a matrix `y2` vector of y end coordinates, if x1 is not a matrix `longlat` if FALSE, Euclidean distance, if TRUE Great Circle distance `prev` if TRUE and x1 is a trip, the return value has a padded end value (\"prev\"ious), rather than start (\"next\")

### Details

If `x1` is a trip object, arguments `x2`, `x3`, `y2` are ignored and the return result has an extra element for the start point of each individual trip, with value 0.0.

The `prev` argument is ignore unless x1 is a trip.

Distance values are in the units of the input coordinate system when longlat is FALSE, and in kilometres when longlat is TRUE.

This originally used `spDistsN1`, then implemented the sp `gcdist` source directly in R, and now uses `geodist`.

Please see the traipse package for a more modern approach.

### Value

Vector of distances between coordinates.

### References

Original source taken from sp package, but now using Helmert from Karney (2013) see the geodist package.

### Examples

`````` d <- data.frame(x=1:10, y=rnorm(10), tms=Sys.time() + 1:10, id=gl(2, 5))
tr <- trip(d, c("tms", "id"))

## the method knows this is a trip, so there is a distance for every
## point, including 0s as the start and at transitions between
## individual trips
trackDistance(tr)

## the default method does not know about the trips, so this is
##(n-1) distances between all points
trackDistance(coordinates(tr), longlat = FALSE)

## we get NA at the start, end and at transitions between trips

angles <- trackAngle(tr)
``````

trip documentation built on July 9, 2023, 7:29 p.m.