XploRe Help : grbiplot

Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Library:	graphic
See also:	svd grandrews grpcp grstar grsurface

Macro:		grbiplot
Description:		Generates a graphical object containing the coordinates for the biplot of a given matrix.

Link:

Introduction to the graphic library

Usage:	`y = grbiplot(x,r,k)`
Input:
	`x`	n x p matrix (n >= p) (n cases, p variables)
	`r`	number, rank of approximation (d <= p)
	`k`	number, 0 <= k <= 1
Output:
	`b`	n+p x d matrix, containing the coordinates for the biplot

Note:

A biplot is a graphical representation of a data set x, where the columns of x represent the variables and the rows represent the cases. For a biplot the matrix x is decomposed, so that approximatly holds x = a*b' where: a = u_1 * l_1^k ~ u_2 * l_2^k ~ ... ~u_r * l_r^k b = v_1 * l_1^(1-k) ~ v_2 * l_2^(1-k) ~ ... ~v_r * l_r^(1-k) u_i = left Eigenvectors of x v_i = right Eigenvectors of x l_i = Eigenvalues of x with: 0<=k<=1 and r<=p r is known as the rank of approximation. The vectors in the rows of a are used to plot the coordinates of the n cases, and the rows of b are the coordinates for plotting the p variables. x must be a n x p matrix

Example:

; loads the library graphic library("graphic") ; reset the random generator randomize(0) ; generate a normal distributed dataset with ; 5 rows and 3 columns x = normal(5,3) ; produce a biplot in 2-space b = grbiplot(x, 2, 0.5) ; create a display with one window d = createdisplay(1,1) ; show the biplot in a display show(d,1,1,b)

Result:


shows a biplot

Library:	graphic
See also:	svd grandrews grpcp grstar grsurface

Keywords - Function groups - @ A B C D E F G H I J K L M N O P Q R S T U V W X Y Z

Author: Torsten Kleinow, 961209