scaleTable: Scales a table according to the Sum and Scale column.

In ralmond/CPTtools: Tools for Creating Conditional Probability Tables

Scales a table according to the Sum and Scale column.

Description

Takes a matrix or vector with a Sum and Scale column and rescales it by multiplying each remaining element by the value of Scale/Sum for that row.

If the last two rows are not named Sum and Scale then it simply returns its argument.

Usage

scaleTable(table)

Arguments

table

A matrix or vector in which the last two columns are named "Scale" and "Sum".

Details

The parameters of a Dirichlet distribution can be stored in two ways, one is to have each cell in the table represent a pseudo count. The other was is to have each row represent a probability vector and use an additional pseudo sample size (the Scale column). If the probability vector is reported in a some other metric (say as a percentage or as a fraction of some smaller sample) the the Sum column is used to store the row sum.

Value

Rescaled table with Sum and Scale columns removed. This makes some attempt to preserve the type of the table argument as a matrix, row vector or numeric object.

Note

Used by the function compareDS to compare tables which may be in different formats.

Author(s)

Russell Almond

References

http://research.ets.org/~ralmond/StatShop/dataFormats.html

Examples

  c1 <- matrix(c(70,20,10,10,20,70),nrow=2,byrow=TRUE,
               dimnames=list(NULL,c("H","M","L")))
  s1 <- matrix(c(7,2,1,10,100,1,2,7,10,100),nrow=2,byrow=TRUE,
               dimnames=list(NULL,c("H","M","L","Sum","Scale")))

  ## 1 row matrixes need special handling (c1[1,] is a vector not a matrix)
  c1r1 <- matrix(c1[1,],nrow=1,dimnames=list(NULL,c("H","M","L")))
  s1r1 <- matrix(s1[1,],nrow=1,dimnames=list(NULL,c("H","M","L","Sum","Scale")))

  stopifnot(
    identical(c1,scaleTable(s1)),
    identical(c1[1,],scaleTable(s1[1,])),
    identical(c1r1,scaleTable(s1r1))
  )

  # This should have no effect when run on matrixes without the Sum and
  # Scale column.
  stopifnot(
    identical(c1,scaleTable(c1)),
    identical(c1[1,],scaleTable(c1[1,])),
    identical(c1r1,scaleTable(c1r1))
  )

ralmond/CPTtools documentation built on Dec. 27, 2024, 7:15 a.m.