Per-trajectory reference direction of a Tracks

The reference direction (unit-circle radians) against which each trajectory's relative frame (`rel_theta`/`rel_x`/`rel_y`) is defined. Trajectories with no recorded reference default to `0` (relative frame equals absolute frame).

Usage

reference(x)

# S4 method for class 'Tracks'
reference(x)

Arguments

x

A [`Tracks`].

Value

For `reference()`, a data frame with `id` and `ref_theta` (or `NULL` when none is set).

See also

[set_reference()], [derive_coords()]