# corLocal: Local correlation coefficient In raster: Geographic Data Analysis and Modeling

 corLocal R Documentation

## Local correlation coefficient

### Description

Local correlation coefficient for two RasterLayer objects (using a focal neighborhood) or for two RasterStack or Brick objects (with the same number of layers (> 2))

### Usage

``````## S4 method for signature 'RasterLayer,RasterLayer'
corLocal(x, y, ngb=5,
method=c("pearson", "kendall", "spearman"), test=FALSE, filename='', ...)

## S4 method for signature 'RasterStackBrick,RasterStackBrick'
corLocal(x, y,
method=c("pearson", "kendall", "spearman"), test=FALSE, filename='', ...)
``````

### Arguments

 `x` RasterLayer or RasterStack/RasterBrick `y` object of the same class as `x`, and with the same number of layers `ngb` neighborhood size. Either a single integer or a vector of two integers c(nrow, ncol) `method` character indicating which correlation coefficient is to be used. One of `"pearson"`, `"kendall"`, or `"spearman"` `test` logical. If `TRUE`, return a p-value `filename` character. Output filename (optional) `...` additional arguments as for `writeRaster`

RasterLayer

### Note

`NA` values are omitted

`cor`, `cor.test`

### Examples

``````b <- stack(system.file("external/rlogo.grd", package="raster"))
b <- aggregate(b, 2, mean)

set.seed(0)
b[[2]] <- flip(b[[2]], 'y') + runif(ncell(b))
b[[1]] <- b[[1]] + runif(ncell(b))

x <- corLocal(b[[1]], b[[2]], test=TRUE )
# plot(x)

# only cells where the p-value < 0.1
plot(xm)

# for global correlation, use the cor function
x <- as.matrix(b)
cor(x, method="spearman")

# use sampleRegular for large datasets
x <- sampleRegular(b, 1000)
cor.test(x[,1], x[,2])

# RasterStack or Brick objects
y <- corLocal(b, flip(b, 'y'))
``````

raster documentation built on Oct. 14, 2023, 5:07 p.m.