Removes out-of-circumference (`rho > 1`) track data so that downstream kinematics (`track_speed()`, `instantaneous_speed()`, `track_length()`, the `path_*` shape metrics, ...) are computed only on the within-circle portion of each trajectory. Distance from the centre, `rho`, is taken from the relative (unit-circle) coordinates `rel_x`/`rel_y`, where `rho = 1` is the circumference.
Usage
restrict_to_circumference(ts, mode = c("truncate", "drop"), max_radius = 1)Arguments
- ts
A `Tracks` carrying relative coordinates (`rel_x`/`rel_y`).
- mode
How to exclude out-of-circumference data per trajectory. `"truncate"` (default) keeps the contiguous prefix up to (excluding) the first point beyond the circumference – the centre-to-circumference approach segment, with no gaps. `"drop"` removes individual beyond-circumference points only; note that dropping interior points lengthens the step bridging the gap, which biases speed and path length, so `"truncate"` is usually preferable for kinematics.
- max_radius
Circumference radius. A point is beyond the circumference when `rho > max_radius` (with a small rim tolerance so points exactly on the circumference are kept). Default `1`.
Value
A new `Tracks` (the input is unmodified) with out-of-circumference rows removed and a `transform_history` entry recording the operation. Trajectories reduced to no rows are dropped.