R Graphical Manual

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Last data update: 2014.03.03

R: Symbol Plot

symbol.plot

R Documentation

Symbol Plot

Description

The function symbol.plot plots the (two-dimensional) data using different symbols according to the robust mahalanobis distance based on the mcd estimator with adjustment.

Usage

symbol.plot(x, quan=1/2, alpha=0.025, ...)

Arguments

`x`	two dimensional matrix or data.frame containing the data.
`quan`	amount of observations which are used for mcd estimations. has to be between 0.5 and 1, default ist 0.5
`alpha`	amount of observations used for calculating the adjusted quantile (see function arw).
`...`	additional graphical parameters

Details

The function symbol.plot plots the (two-dimensional) data using different symbols. In addition a legend and four ellipsoids are drawn, on which mahalanobis distances are constant. As the legend shows, these constant values correspond to the 25%, 50%, 75% and adjusted (see function arw) quantiles of the chi-square distribution.

Value

`outliers`	boolean vector of outliers
`md`	robust mahalanobis distances of the data

Author(s)

Moritz Gschwandtner <e0125439@student.tuwien.ac.at>
Peter Filzmoser <P.Filzmoser@tuwien.ac.at> http://www.statistik.tuwien.ac.at/public/filz/

References

P. Filzmoser, R.G. Garrett, and C. Reimann. Multivariate outlier detection in exploration geochemistry. Computers & Geosciences, 31:579-587, 2005.

Examples

# create data:
x <- cbind(rnorm(100), rnorm(100))
y <- cbind(rnorm(10, 5, 1), rnorm(10, 5, 1))
z <- rbind(x,y)
# execute:
symbol.plot(z, quan=0.75)