popdemo provides tools for modelling populations and demography using
matrix projection models (MPMs), with deterministic and stochastic model
implementations. These tools include population projection, indices of short-
and long-term population size and growth, perturbation analysis, convergence
to stability or stationarity, and diagnostic and manipulation tools. This includes:
popdemo provides a simple means of projecting and plotting PPM models.
project provides a means to project and plot population
dynamics of both deterministic and stochastic models. Many methods are available
for working with population projections: see Projection-class and
Projection-plots
The eigs function provides a simple means to calculate asymptotic
population dynamics using matrix eigenvalues.
There are functions for calculating transient dynamics at various points of
the population projection. reac measures immediate transient
density of a population (within the first time step). maxamp,
maxatt are near-term indices that measure the largest and
smallest transient dynamics a population may exhibit overall, respectively.
codeinertia measures asymptotic population density relative to stable
state, and has many perturbation methods in the package (see below). All transient
indices can be calculated using specific population structures, as well as bounds on
population size.
Methods for linear perturbation (sensitivity and elasticity) analysis of asymptotic dynamics
are available through the sens, tfs_lambda and tfsm_lambda
functions. Elasticity analysis is also available using the elas function.
Sensitivity analysis of transient dynamics is available using the tfs_inertia
and tfsm_inertia functions.
Methods for nonlinear perturbation (transfer function) analysis of asymptotic
dynamics is achieved using tfa_lambda and tfam_lambda,
whilst transfer function analysis of transient dynamics is available with
tfa_inertia and tfam_inertia. These all have
associated plotting methods linked to them: see plot.tfa and
plot.tfam).
Information on the convergence of populations to stable state can be useful, and
popdemo provides several means of analysing convergence.
dr measures the damping ratio, and there are several distance measures available
(see KeyfitzD, projectionD and
CohenD). There is also a means of calculating convergence time
through simulation: convt.
isPrimitive, isIrreducible and
isErgodic facilitate diagnosis of matrix properties
pertaining to ergodicity.
Matlab2R allows coding of matrices in a Matlab style, which
also facilitates import of multiple matrices simultaneously if comma-seperated
files are used to import dataframes. Its analogue, R2Matlab,
converts R matrices to Matlab-style strings, for easier export.