Cassini {clue}

Cassini Data

Description

A Cassini data set with 1000 points in 2-dimensional space which are drawn from the uniform distribution on 3 structures. The two outer structures are banana-shaped; the “middle” structure in between them is a circle.

Usage

data("Cassini")

Format

A classed list with components

x

a matrix with 1000 rows and 2 columns giving the coordinates of the points.

classes

a factor indicating which structure the respective points belong to.

Details

Instances of Cassini data sets can be created using function mlbench.cassini in package mlbench. The data set at hand was obtained using

    library("mlbench")
    set.seed(1234)
    Cassini <- mlbench.cassini(1000)
  

Examples

data("Cassini")
op <- par(mfcol = c(1, 2))
## Plot the data set:
plot(Cassini$x, col = as.integer(Cassini$classes),
     xlab = "", ylab = "")
## Create a "random" k-means partition of the data:
set.seed(1234)
party <- kmeans(Cassini$x, 3)
## And plot that.
plot(Cassini$x, col = cl_class_ids(party),
     xlab = "", ylab = "")
## (We can see the problem ...)
par(op)