# scalefactor: Scaling Factor In cplots: Plots for Circular Data

## Description

The function calculates the scaling factor so that after scaling the original density curve (before transformation), the total area after transformation (excluding the reference circle) has the specified value.

## Usage

 `1` ```scalefactor(x, radius = 0, total.area = 1, area.prop = TRUE) ```

## Arguments

 `x` a numeric vector storing the heights of a density curve or a histogram. `radius` the radius of the reference circle. `total.area` a positive number specifying the total area. `area.prop` logical; if `TRUE`, an area-proportional transformation is applied; if `FALSE`, a height-proportional transformationis applied.

## Details

Each value in x is a density value before transformation, for points equally-spaced on [0,2π). For a smooth density curve, use a reasonably large number of points, equally-spaced on [0,2π). The area under the density curve after transformation is then approximated by that of the corresponding sectors. Note if `area.prop = TRUE`, the scale factor is simply the value of `total.area`.

## Author(s)

Danli Xu <dxu452@aucklanduni.ac.nz>, Yong Wang <yongwang@auckland.ac.nz>

## References

Xu, D. and Wang, Y. (2019) Area-proportional Visualization for Circular Data (submitted).

## See Also

`circtrans`

## Examples

 ```1 2 3 4 5 6 7 8``` ```dvm = function(x, mu=0, kappa=1) # von Mises density exp(kappa * cos(x - mu)) * (2 * pi * besselI(kappa, 0))^(-1) x = dvm(seq(0, 2 * pi, len = 100), pi, 10) scalefactor(x) # area-proportional transformation scalefactor(x, area.prop = FALSE) # height-proportional transformation scalefactor(x, total.area = 2) # total area of 2 scalefactor(x, area.prop = FALSE, total.area = 2) ```

cplots documentation built on May 2, 2019, 12:19 p.m.