popdemo-package:
Demographic Modelling Using Projection Matrices
Description
This package provides a set of tools designed for modelling population demography
using population projection matrix (PPM) models. The focus is mainly on indices of transient dynamics,
and the use of control theory (specifically transfer functions). However,
popdemo includes a number of tools focussing on other areas of demographic
modelling. Some tools may prove useful to anyone working with
projection matrix models of any type, or indeed matrices in general.
The package is designed to build on those tools already available in popbio.
Details
|
Package: |
| popdemo |
|
Type: |
| Package |
|
Version: |
| 1.0 |
|
Date: |
| 2011-05-12 |
|
License: |
| GPL-2 |
|
LazyLoad: |
| yes |
Selected functions (see bottom of page for a link to the full index):
Functions useful for working with matrices:
popdemo contains a number of tools to ease working with matrices
(and specifically PPMs) in R.
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.
is.matrix_primitive, is.matrix_irreducible and
is.matrix_ergodic facilitate diagnosis of matrix properties
pertaining to ergodicity.
Population projection:
popdemo provides a simple means of projecting and plotting PPM models.
project will project population dynamics and a plotting method
is available via plot.projection.
Indices of transient density:
Transient dynamics are important to study in PPM models, and popdemo
provides the means to work with transient indices of PPM models.
reactivity, firststepatt measure immediate transient
density of a population (within the first time step). maxamp and
maxatt are near-term indices that measure the largest and smallest
transient dynamics a population may exhibit overall.
inertia measures asymptotic population density relative to stable
state, and has many perturbation methods in the package (see below). All indices
can be calculated using specific population structures, as well as bounds on
population size.
Perturbation analysis:
Perturbation analysis is a key part of population studies. popdemo provides
methods for nonlinear perturbation analysis of both asymptotic dynamics, using tfa and
tfamatrix, and transient dynamics, using inertia.tfa and
inertia.tfamatrix. These all have associated plotting methods linked to them: see
plot.tfa and plot.tfamatrix). Sensitivity analyses are also available
using transfer function methods: see tfsens, tfsensmatrix,
inertia.tfsens and inertia.tfsensmatrix. (Traditional perturbation
analyses are also available: sens, elas).
Indices of convergence:
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 Keyfitz.delta, projection.distance and
Cohen.cumulative). There is also a means of calculating convergence time
through simulation: convergence.time.