PP3init {PP3} | R Documentation |
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.
PP3init(xm, action = 0, limit = 3)
xm |
Data matrix containing K rows (variables) and N columns (observations). |
action |
Possible outlier action. See help to |
limit |
Possible outlier action. See help to |
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.
# # Not designed for direct user use, but here is an example # # # The flea beetle data # data(beetle) # # Initialise the PP3 system for this data # tmp <- PP3init(t(beetle)) # # This object contains the ansT and ansU third- and fourth-order tensors #