movpotential_ews {earlywarnings}

Moving Average Potential

Description

This function reconstructs a potential derived from data along a gradient of a given parameter.

Usage

movpotential_ews(
  X,
  param = NULL,
  bw = "nrd",
  bw.adjust = 1,
  detection.threshold = 0.1,
  std = 1,
  grid.size = 50,
  plot.cutoff = 0.5,
  plot.contours = TRUE,
  binwidth = 0.2,
  bins = NULL
)

Arguments

X

a vector of the X observations of the state variable of interest

param

parameter values corresponding to the observations in X

bw

Bandwidth for smoothing kernels. Automatically determined by default.

bw.adjust

Bandwidth adjustment constant

detection.threshold

Threshold for local optima to be discarded.

std

Standard deviation.

grid.size

number of evaluation points; number of steps between min and max potential; also used as kernel window size

plot.cutoff

cuttoff for potential minima and maxima in visualization

plot.contours

Plot contours on the landscape visualization

binwidth

binwidth for contour plot

bins

bins for contour plot. Overrides binwidth if given

Value

A list with the following elements: pars values of the covariate parameter as matrix; xis values of the x as matrix; pots smoothed potentials; mins minima in the densities (-potentials; neglecting local optima); maxs maxima in densities (-potentials; neglecting local optima); plot an object that displays the potential estimated in 2D

Author(s)

L. Lahti, E. van Nes, V. Dakos.

References

Hirota, M., Holmgren, M., van Nes, E.H. & Scheffer, M. (2011). Global resilience of tropical forest and savanna to critical transitions. Science, 334, 232-235.

Examples

X <- c(rnorm(1000, mean = 0), rnorm(1000, mean = -2), rnorm(1000, mean = 2));
param <- seq(0,5,length=3000); 
res <- movpotential_ews(X, param)