vecr2matr {bayesSurv} | R Documentation

## Transform single component indeces to double component indeces

### Description

Components of a bivariate G-spline can be indexed in several ways. Suppose that the knots in the first dimension are mu[1,-K1],...,mu[1,K1] and the knots in the second dimension mu[2,-K2],...,mu[2,K2]. I.e. we have 2*K[1]+1 knots in the first dimension and 2*K[2]+1 knots in the second dimension. Each G-spline component can have a double index (k[1],k[2]) assigned which means that it corresponds to the knot (mu[1,k1], mu[2,k2]) or alternatively the same G-spline component can have a~single index

r=(k[2]+K[2])*(2*K[1]+1) + k[1] + K[1] + 1

assigned where r takes values from 1,...,K[1]*K[2]. Single indexing is used for example by files `r.sim` and `r_2.sim` generated by functions `bayesHistogram`, `bayesBisurvreg`, `bayessurvreg2` to save some space.

This function serves to translate single indeces to double indeces using the relationship

k[1] = (r-1) %% (2*K[1]+1) - K[1]

k[2] = (r-1) % % (2*K[1]+1) - K[2]

The function can be used also in one dimensional case when a~simple relationship holds

r = k + K + 1

k = r - 1 - K

### Usage

    vecr2matr(vec.r, KK)

### Arguments

`vec.r` | a~vector of single indeces
`KK` | a~vector with numbers of knots on each side of the central knot for each dimension of the G-spline. The length of `KK` determines dimension of the G-spline

### Value

In bivariate case: a~matrix with two columns and as many rows as the length of `vec.r`.
In univariate case: a~vector with as ,amy components as the length of `vec.r`.

### Author(s)

Arnost Komarek arnost.komarek@med.kuleuven.be

### Examples

    ### Bivariate G-spline
    ### with 31 knots in each dimension
    KK <- c(15, 15)

    ### First observation in component (-15, -15),
    ### second observation in component (15, 15),
    ### third observation in component (0, 0)
    vec.r <- c(1, 961, 481)
    vecr2matr(vec.r, KK)

[Package bayesSurv version 0.4 Index]