ellipseFromScatter: Create segments of an ellipse around points on a 2D plane

In dmattek/tca-package: Time Course Analyzer

Description

Create segments of an ellipse around points on a 2D plane

Usage

ellipseFromScatter(in.mat, in.group, in.col.sel = 1:2, in.scale = 1,
  in.prob = 0.68)

Arguments

in.mat	matrix with point coordinates. Rows correspond to points, columns to dimensions.
in.group	vector with grouping. Must be of the same length as the number of rows in the input matrix.
in.col.sel	vector to select columns from the input matrix. Must be of length 2.
in.scale	scale factor to apply to observations (see param obs.scale in ggbiplot manual https://www.rdocumentation.org/packages/ggbiplot/versions/0.55/topics/ggbiplot)
in.prob	size of the ellipse in Normal probability (see param ellipse.prob in ggbiplot manual)

Value

data frame with first two columns with corrdinates of points of an ellipse, and column 'group' with groupings as provided by 'in.group' vector.

Examples

## Draw red ellipse around scatter plot
n.pts = 50
n.cols = 2
m.gauss = matrix(rnorm(n.pts * n.cols), n.pts)
df.ell = ellipseFromScatter(m.gauss, rep(1, n.pts))
require(ggplot2)
ggplot(as.data.frame(m.gauss), aes(V1, V2)) +
  geom_point() +
  geom_path(data = df.ell, aes(X1, X2), color = 'red')

## Fill the ellipse with colour
require(dplyr)
df.hull <- df.ell %>%
  do(.[chull(.[1:2]), ])

ggplot(as.data.frame(m.gauss), aes(V1, V2)) +
  geom_point() +
  geom_polygon(data = df.hull, aes(X1, X2), color = 'red', fill = 'red', alpha = 0.5)

dmattek/tca-package documentation built on Dec. 10, 2019, 4:10 p.m.