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Given a set of locations defining a trajectory, this function approximates their instantaneous headings computed as the direction of the vectors between successive locations along the trajectory.

Usage

heading(x, y, geo = FALSE)

Arguments

x

A vector of x (or longitude) coordinates corresponding to a single trajectory.

y

A vector of y (or latitude) coordinates corresponding to a single trajectory.

geo

A logical value indicating whether the locations are defined by geographic coordinates (pairs of longitude/latitude values). Default: FALSE.

Value

A vector of the same length as x and y corresponding to the approximated headings along the trajectory.

See also

Author

Simon Garnier, garnier@njit.edu

Examples

x <- rnorm(25)
y <- rnorm(25, sd = 3)
heading(x, y)
#>  [1]          NA -1.25929093  2.28416873  1.66769775 -2.02116749  0.78349635
#>  [7]  2.54168267  0.07308071 -1.29115309 -1.65437433  1.62121152 -1.56887406
#> [13]  0.71555923 -2.41995361  1.64635191  1.10715877 -1.63370975 -0.37132905
#> [19]  0.65822319  2.83369532  1.01450472  1.74093488 -1.97611127 -1.51830078
#> [25]  1.67101453