Radian conversion helpers

Small helpers for the circ_gam data contract: the response, and any angular covariate entering a cyclic smooth, must be in radians. rad converts to radians from a named or numeric period, deg converts radians to degrees, and wrap folds angles to a single branch with atan2(sin, cos) (exact and NA-safe).

Usage

rad(x, from = "degrees")

deg(x)

wrap(x, to = c("pi", "2pi"))

Arguments

x

A numeric vector of angles.

from

For rad, the period of the input scale: one of "degrees" (360), "gradians" (400), "turns" (1), "radians" (a no-op), or any positive numeric period – e.g. 24 for hour-of-day, 12 for month.

to

For wrap, the target branch: "pi" for \((-\pi, \pi]\) (the tan-half branch) or "2pi" for \([0, 2\pi)\).

Value

A numeric vector the same length as x.

See also

circ_gam

Examples

rad(c(0, 90, 180, 270))     # degrees -> radians
rad(c(0, 6, 12, 18), 24)    # hour-of-day -> radians
deg(pi)                     # 180
wrap(3 * pi)                # pi
wrap(-0.5, "2pi")           # 2*pi - 0.5