| lifespan {exactLTRE} | R Documentation |
Expected lifespan
Description
The expected lifespan vector is calculated by multiplying a column of ones by the fundamental matrix. The fundamental matrix, generally referred to as N, contains the expected number of timesteps that an individual will spend in each age, stage, or size class of the matrix, given their current state.
Usage
lifespan(Umat, all_ages = TRUE)
Arguments
Umat |
The survival components of the population projection matrix |
all_ages |
User specifies whether the function should return the expected lifespan remaining for all ages (all_ages="T") or only the expected lifespan at birth (all_ages="F"). |
Details
The expected lifespan vector contains the expected lifespan remaining for an individual in each age, stage, or size class of the population. If the user requests only the expected lifespan from birth, then only the first entry of the expected lifespan vector is returned.
Value
The expected lifespan is either a vector (if all_ages="T") or a single number for the expected lifespan of a newly born individual (if all_ages="F"). Expected lifespan is given in the same units as the projection time step. If the projection interval is two weeks, the lifespan will be the number of two-week intervals that an individual is expected to survive. You may wish to convert to a standard time step, like days or years.
Examples
A1<- matrix(data=c(0,0.8,0, 0,0,0.7, 5,0,0.2), nrow=3, ncol=3)
U1<- A1
U1[1,3]<- 0
# the upper right corner represents adult fertility in this model. U1, the
# survival matrix, contains all the transitions *except* for fertility.
eta<- lifespan(U1, all_ages=TRUE)
eta_1<- lifespan(U1, all_ages=FALSE) # eta_1 should match the first entry of eta