Returns a population of individuals alive.
population_alive(population, t, a1 = 0, a2 = Inf)
A population data frame containing at least a column 'birth'
and 'death'
.
A numeric indicating the time.
0 by default. All individuals of age over a1
at t
are selected.
Inf by default. All individuals of age below a2
at t
are selected.
The function returns a population data frame containing all individuals alive at time t
and of age in [a1,a2)
.