PP3init: Initialize projection pursuit code
In PP3: Three-Dimensional Exploratory Projection Pursuit

Description Usage Arguments Details Value Author(s) References See Also Examples

Initialize projection pursuit code. This function only need be executed once. Then subsequent calls to projection index calculation can reuse the results of this initialization many times.

1	PP3init(xm, action = 0, limit = 3)

`xm`	Data matrix containing K rows (variables) and N columns (observations).
`action`	Possible outlier action. See help to `PP3many` for description.
`limit`	Possible outlier action. See help to `PP3many` for description.

This function spheres the data and calculates third- and fourth-order moment quantities, which can be used for subsequent index calculation.

A list with the following components.

`COPYN`	An integer less than or equal to the number of columns of the input matrix. The number of points that were kept after outlier processing (for index computation only).
`ansT`	The three-dimensional T summary statistic array
`ansU`	The four-dimensional U summary statistic array

G. P. Nason

Friedman, J.H. and Tukey, J.W. (1974) A projection pursuit algorithm for exploratory data analysis. IEEE Trans. Comput., 23, 881-890.

Jones, M.C. and Sibson, R. (1987) What is projection pursuit? (with discussion) J. R. Statist. Soc. A, 150, 1-36.

Nason, G. P. (1995) Three-dimensional projection pursuit. J. R. Statist. Soc. C, 44, 411-430.

Nason, G. P. (2001) Robust projection indices. J. R. Statist. Soc. B, 63, 551-567.

PP3many

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# Not designed for direct user use, but here is an example
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# The flea beetle data
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data(beetle)
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# Initialise the PP3 system for this data
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tmp <- PP3init(t(beetle))
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# This object contains the ansT and ansU third- and fourth-order tensors
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