addXPtr: Adds constant to the elements of a XPtr object vector-wise

In rrp: Random Recursive Partitioning

Description

Adds constant to the elements of a XPtr object vector-wise. The idea is that a symmetrix matrix M can be represented as a triangular object d. With this function you set M[x,x] = M[x,x] + k but instead of working on M this function works on its XPtr representation d.

Usage

addXPtr(d, x, k)

Arguments

d	a XPtr object, lower diagonal, representing a symmetric matrix
x	a list of vectors of indices
k	a vector of constants to add, arguments are eventually recycled silently

Value

returns the modified XPtr object

Author(s)

Stefano M. Iacus

See Also

dist

Examples

M <- matrix(0,5,5)
d <- newXPtr(5,0)
x <- list(1:3, 4:5)

addXPtr(d,x,c(-1,+1))

# which is the equivalent of (apart for the diagonal elements)
M[1:3,1:3] <- M[1:3,1:3] - 1
M[4:5,4:5] <- M[4:5,4:5] + 1

# Indeed, we have
(XPtrToDist(d))
as.dist(M)

rrp documentation built on May 2, 2019, 5:25 p.m.