linear_MODP: Modified Orthogonal Discriminant Projection

In Rdimtools: Dimension Reduction and Estimation Methods

Modified Orthogonal Discriminant Projection

Description

Modified Orthogonal Discriminant Projection (MODP) is a variant of Orthogonal Discriminant Projection (ODP). Authors argue the assumption in modeling ODP's mechanism to reflect distance and class labeling seem unsound. They propose a modified method to explore the intrinsic structure of original data and enhance the classification ability.

Usage

do.modp(
  X,
  label,
  ndim = 2,
  preprocess = c("center", "scale", "cscale", "decorrelate", "whiten"),
  type = c("proportion", 0.1),
  symmetric = c("union", "intersect", "asymmetric"),
  alpha = 0.5,
  beta = 10
)

Arguments

X	an (n\times p) matrix or data frame whose rows are observations and columns represent independent variables.
label	a length-n vector of data class labels.
ndim	an integer-valued target dimension.
preprocess	an additional option for preprocessing the data. Default is "center". See also aux.preprocess for more details.
type	a vector of neighborhood graph construction. Following types are supported; c("knn",k), c("enn",radius), and c("proportion",ratio). Default is c("proportion",0.1), connecting about 1/10 of nearest data points among all data points. See also aux.graphnbd for more details.
symmetric	one of "intersect", "union" or "asymmetric" is supported. Default is "union". See also aux.graphnbd for more details.
alpha	balancing parameter of non-local and local scatter in [0,1].
beta	scaling control parameter for distant pairs of data in (0,∞).

Value

a named list containing

Y

an (n\times ndim) matrix whose rows are embedded observations.

projection

a (p\times ndim) whose columns are basis for projection.

trfinfo

a list containing information for out-of-sample prediction.

References

\insertRef

zhang_modified_2011Rdimtools

Examples

## generate 3 different groups of data X and label vector
x1 = matrix(rnorm(4*10), nrow=10)-20
x2 = matrix(rnorm(4*10), nrow=10)
x3 = matrix(rnorm(4*10), nrow=10)+20
X     = rbind(x1, x2, x3)
label = rep(1:3, each=10)

## try different beta (scaling control) parameter
out1 = do.modp(X, label, beta=1)
out2 = do.modp(X, label, beta=10)
out3 = do.modp(X, label, beta=100)

## visualize
opar <- par(no.readonly=TRUE)
par(mfrow=c(1,3))
plot(out1$Y, main="MODP::beta=1")
plot(out2$Y, main="MODP::beta=10")
plot(out3$Y, main="MODP::beta=100")
par(opar)

Rdimtools documentation built on Dec. 28, 2022, 1:44 a.m.