# cdensity: Circular Density Curve In cplots: Plots for Circular Data

 cdensity R Documentation

## Circular Density Curve

### Description

Function `cdensity` can be used to plot 2-dimensional density curves for circular data.

### Usage

```cdensity(
f,
area.prop = TRUE,
total.area = 1,
nlabels = 4,
n = 500,
col = "red",
xlim = NULL,
ylim = NULL,
main = NULL
)
```

### Arguments

 `f` an R function that is to be plotted as a circular density or frequency. `radius` the radius of the reference circle. If `radius = 0`, no reference circle is produced, and the centre presents the point with zero density. `area.prop` logical; if `TRUE`, an area-proportional transformation is applied; if `FALSE`, a height-proportional transformation is applied. `total.area` a positive number specifying the total area under the density curve. If `total.area = NULL`, no scaling is applied, the plot is in the original scale. If `area.prop = TRUE`, the total area is automatically unity without scaling. `nlabels` integer, for the number of levels to be plotted; if `0`, no label is plotted. `add` logical; if `TRUE`, the density curve is superimposed to the current plot, for example, a circular histogram, a rose diagram or a stacked dot plot that has been produced in a similar manner. `n` the number of points to plot the density curve. `col` the color of the density line. `xlim` numeric vectors of length 2, giving the x coordinates ranges. `ylim` numeric vectors of length 2, giving the y coordinates ranges. `main` the main title (on top)

No return value

### Author(s)

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

### References

Xu, D. and Wang, Y. (2020). Area-proportional Visualization for Circular Data. Journal of Computational and Graphical Statistics, 29, 351-357.

`cbarplot`, `cdotplot`, `chist`

### Examples

```# 600 observations from two von Mises distributions
library(circular)
x = c(rvonmises(200, circular(pi/4), 5), rvonmises(400, circular(pi), 20))
dvm = function(x, mu=0, kappa=1)   # von Mises density
exp(kappa * cos(x - mu)) * (2 * pi * besselI(kappa, 0))^(-1)
f = function(x) 1/3 * dvm(x, pi/4, 5) + 2/3 * dvm(x, pi, 20)

cdensity(f)                # plot the density in an area-proportional manner

chist(x)                   # circular histogram
cdensity(f, add=TRUE)      # superimpose the density curve
chist(x, area=FALSE)       # height-proportional circular histogram
cdensity(f, area=FALSE, add=TRUE)   # superimpose the density curve