% Generated by roxygen2: do not edit by hand
% Please edit documentation in R/morans.plot.R
\name{morans.plot}
\alias{morans.plot}
\title{Autocorrelation Plot}
\usage{
morans.plot(
  x,
  y = NULL,
  coords = NULL,
  type.ac = c("xy", "yx"),
  dist.function = "inv.power",
  scale.xy = TRUE,
  scale.morans = FALSE,
  ...
)
}
\arguments{
\item{x}{Vector of x response variables}

\item{y}{Vector of y response variables}

\item{coords}{A matrix of coordinates corresponding to [x,y]}

\item{type.ac}{Type of autocorrelation plot ("xy", "yx")}

\item{dist.function}{("inv.power", "neg.exponent")}

\item{scale.xy}{(TRUE/FALSE) scale the x,y vectors}

\item{scale.morans}{(FALSE/TRUE) standardize the Moran's index to an 
expected [-1 to 1]?}

\item{...}{Additional arguments passed to plot}
}
\value{
A plot of the scaled variable against its spatially lagged values.
}
\description{
Autocorrelation plot (Anselin 1996), following Chen (2015), 
             aka, Moran's-I plot (univariate or bivariate)
}
\details{
The argument "type" controls the plot for x influencing y (type="xy") or y 
influencing x (type="yx"). If y is not defined then the statistic is univariate 
and only the "xy" plot will be available. The linear relationship between x and 
its spatial lag (Wx) is indicative of the spatial autoregressive process, underlying 
the spatial dependence. The statistic can be autocorrelation (univariate or 
cross-correlation (bivariate). The quadrants are the zero intercept for random 
autocorrelation and the red line represents the trend in autocorrelation. The quadrants 
in the plot indicate the type of spatial association/interaction (Anselin 1996). 
For example the upper-left quadrant represents negative associations of low values 
surrounded by high and the lower-right quadrant represents negative associations of
high values surrounded by low.  

If y is not specified the univariate statistic for x is returned. the coords argument 
is only used if k = NULL. Can also be an sp object with relevant x,y coordinate slot 
(ie., points or polygons). If w = NULL, the default method for deriving spatial weights 
matrix, options are: inverse power or negative exponent. If scale.xy = FALSE it is 
assumed that they are already scaled following Chen (2015).
}
\examples{
 p = c("sf", "sp", "spdep")
 if(any(!unlist(lapply(p, requireNamespace, quietly=TRUE)))) { 
   m = which(!unlist(lapply(p, requireNamespace, quietly=TRUE)))
   message("Can't run examples, please install ", paste(p[m], collapse = " "))
 } else {
 invisible(lapply(p, require, character.only=TRUE))
 
 data(meuse, package = "sp")
 meuse <- st_as_sf(meuse, coords = c("x", "y"), crs = 28992, agr = "constant") 

# Autocorrelation (univariate)  
morans.plot(meuse$zinc, coords = st_coordinates(meuse)[,1:2])   

# Cross-correlation of: x influencing y and y influencing x
opar <- par(no.readonly=TRUE)
  par(mfrow=c(1,2)) 
    morans.plot(x=meuse$zinc, y=meuse$copper, coords = st_coordinates(meuse)[,1:2], 
                scale.morans = TRUE)
    morans.plot(x=meuse$zinc, y=meuse$copper, coords = st_coordinates(meuse)[,1:2],
                scale.morans = TRUE, type.ac="yx") 
par(opar)
}                       
}
\references{
Chen., Y. (2015) A New Methodology of Spatial Cross-Correlation Analysis. 
  PLoS One 10(5):e0126158. doi:10.1371/journal.pone.0126158
 
Anselin, L. (1996) The Moran scatterplot as an ESDA tool to assess local instability 
  in spatial association. pp. 111-125 in M. M. Fischer, H. J. Scholten and D. Unwin (eds) 
  Spatial analytical perspectives on GIS, London, Taylor and Francis

Anselin, L. (1995) Local indicators of spatial association, Geographical Analysis, 
  27:93-115
}
\author{
Jeffrey S. Evans  <jeffrey_evans@tnc.org>
}
