Circular boxplot statistics (Tukey-like, for circular and axial data)
Source:R/circular_boxplot.R
circ_boxplot_stats.RdComputes the five-number summary and fences of a circular boxplot following Buttarazzi, Pandolfo & Porzio (2018): observations are depth-ranked outward from the antimedian, the box spans the central ~50 the median), and the fence multiplier is obtained in closed form from the von Mises quantiles at the sample's estimated concentration (so ~0.7 observations are flagged as far-out under that reference). Pairs with [add_circular_boxplot()] for rendering.
Arguments
- hd
A data frame with a column of heading angles in radians (unit-circle convention), or a numeric vector of angles.
- angle_col
Name of the angle column when `hd` is a data frame. Default `"heading"`.
- axial
Logical. Treat the angles as axial (bidirectional, mod-pi): angles are doubled, the boxplot computed, and locations halved back to `[0, pi)`; the fence multiplier is taken on the doubled data. Default `FALSE`.
Value
A list with `median`, `antimedian`, `hinges`, `box_arc`, `constant`, `kappa`, `fences`, `whiskers`, `far_out` (all radians, unit-circle convention), `n`, `axial`, `drawable`, and `reason`. When `drawable` is `FALSE` (non-unique median or `n < 4`) the location fields are `NA`; `reason` may also carry a non-fatal advisory while `drawable` remains `TRUE` (near-uniform data).
References
Buttarazzi, D., Pandolfo, G. & Porzio, G. C. (2018). A boxplot for circular data. Biometrics 74(4), 1492–1501. doi:10.1111/biom.12889