Weight-based class updates

Usage

update_classes_wb(
  s,
  b,
  Omega,
  epsmin = 0.01,
  epsmax = 0.7,
  deltamin = 0.1,
  deltashift = 0.5,
  identify_classes = FALSE,
  Cmax = 10L
)

Arguments

s: [numeric(C)]
The vector of class weights.
b: [matrix(nrow = P_r, ncol = C)]
The matrix of class means as columns.
Omega: [matrix(nrow = P_r * P_r, ncol = C)]
The matrix of vectorized class covariance matrices as columns.
epsmin: [numeric(1)]
The threshold weight for removing a class.
epsmax: [numeric(1)]
The threshold weight for splitting a class.
deltamin: [numeric(1)]
The threshold difference in class means for joining two classes.
deltashift: [numeric(1)]
The scale for shifting the class means after a split.
identify_classes: [logical(1)]
Identify classes by decreasing class weights?
Cmax: [integer(1)]
The maximum number of classes, used to allocate space.

Value

A list of updated values for s, b, and Omega and the indicator update_type which signals the type of class update:

0: no update
1: removed class
2: split class
3: merged classes

Details

The following updating rules apply:

Class \(c\) is removed if \(s_c < \epsilon_{min}\).
Class \(c\) is split into two classes, if \(s_c > \epsilon_{max}\).
Two classes \(c_1\) and \(c_2\) are merged to one class, if \(||b_{c_1} - b_{c_2}|| < \delta_{min}\).

Examples

s <- c(0.7, 0.3)
b <- matrix(c(1, 1, 1, -1), ncol = 2)
Omega <- matrix(c(0.5, 0.3, 0.3, 0.5, 1, -0.1, -0.1, 0.8), ncol = 2)

### no update
update_classes_wb(s = s, b = b, Omega = Omega)
#> $s
#> [1] 0.7 0.3
#> 
#> $b
#>      [,1] [,2]
#> [1,]    1    1
#> [2,]    1   -1
#> 
#> $Omega
#>      [,1] [,2]
#> [1,]  0.5  1.0
#> [2,]  0.3 -0.1
#> [3,]  0.3 -0.1
#> [4,]  0.5  0.8
#> 
#> $update_type
#> [1] 0
#> 

### remove class 2
update_classes_wb(s = s, b = b, Omega = Omega, epsmin = 0.31)
#> $s
#> [1] 1
#> 
#> $b
#>      [,1]
#> [1,]    1
#> [2,]    1
#> 
#> $Omega
#>      [,1]
#> [1,]  0.5
#> [2,]  0.3
#> [3,]  0.3
#> [4,]  0.5
#> 
#> $update_type
#> [1] 1
#> 

### split class 1
update_classes_wb(s = s, b = b, Omega = Omega, epsmax = 0.69)
#> $s
#> [1] 0.35 0.35 0.30
#> 
#> $b
#>          [,1]      [,2] [,3]
#> [1,] 1.316228 0.6837722    1
#> [2,] 1.316228 0.6837722   -1
#> 
#> $Omega
#>      [,1] [,2] [,3]
#> [1,]  0.5  0.5  1.0
#> [2,]  0.3  0.3 -0.1
#> [3,]  0.3  0.3 -0.1
#> [4,]  0.5  0.5  0.8
#> 
#> $update_type
#> [1] 2
#> 

### merge classes 1 and 2
update_classes_wb(s = s, b = b, Omega = Omega, deltamin = 3)
#> $s
#> [1] 1
#> 
#> $b
#>      [,1]
#> [1,]    1
#> [2,]    0
#> 
#> $Omega
#>      [,1]
#> [1,] 0.75
#> [2,] 0.10
#> [3,] 0.10
#> [4,] 0.65
#> 
#> $update_type
#> [1] 3
#>