Find all possible trajectories through a given multi-state model

For a given multi-state model, specified through a transition matrix, paths recursively finds all the possible trajectories or paths through that multi-state starting from a specified state. DO NOT USE for reversible or cyclic multi-state models.

Usage

paths(trans, start = 1)

Arguments

trans

The transition matrix describing the multi-state model, see msprep

start

The starting state for the trajectories

Value

A matrix, each row of which specifies a possible path through the multi-state model.

Details

The function is recursive. It starts in start, looks at what states can be visited from start, and appends the results of the next call to the current value (matrix). If the transition matrix contains loops, the function will find infinitely many paths, so do not use paths for reversible or cyclic multi-state models. A warning is not yet incorporated!

Author

Hein Putter <H.Putter@lumc.nl>

Examples

tmat <- matrix(NA,5,5)
tmat[1,2:3] <- 1:2
tmat[1,5] <- 3
tmat[2,4:5] <- 4:5
tmat[3,4:5] <- 6:7
tmat[4,5] <- 8
paths(tmat)
#>       [,1] [,2] [,3] [,4]
#>  [1,]    1   NA   NA   NA
#>  [2,]    1    2   NA   NA
#>  [3,]    1    2    4   NA
#>  [4,]    1    2    4    5
#>  [5,]    1    2    5   NA
#>  [6,]    1    3   NA   NA
#>  [7,]    1    3    4   NA
#>  [8,]    1    3    4    5
#>  [9,]    1    3    5   NA
#> [10,]    1    5   NA   NA
paths(tmat, start=3)
#>      [,1] [,2] [,3]
#> [1,]    3   NA   NA
#> [2,]    3    4   NA
#> [3,]    3    4    5
#> [4,]    3    5   NA