raster.kendall: Kendall tau trend with continuity correction for raster...

Description Usage Arguments Details Value Author(s) References See Also Examples

View source: R/raster.kendall.R

Description

Calculates a nonparametric statistic for a monotonic trend based on the Kendall tau statistic and the Theil-Sen slope modification

Usage

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raster.kendall(x, intercept = FALSE, p.value = FALSE, confidence = FALSE,
  tau = FALSE, ...)

Arguments

x

A rasterStack object with at least 5 layers

intercept

(FALSE/TRUE) return a raster with the pixel wise intercept values

p.value

(FALSE/TRUE) return a raster with the pixel wise p.values

confidence

(FALSE/TRUE) return a raster with the pixel wise 95 pct confidence levels

tau

(FALSE/TRUE) return a raster with the pixel wise tau values

...

Additional arguments passed to the raster overlay function

Details

This function implements Kendall's nonparametric test for a monotonic trend using the Theil-Sen (Theil 1950; Sen 1968; Siegel 1982) method to estimate the slope and related confidence intervals.

Value

Depending on arguments, a raster layer or rasterBrick object containing:

Author(s)

Jeffrey S. Evans <[email protected]>

References

Theil, H. (1950) A rank invariant method for linear and polynomial regression analysis. Nederl. Akad. Wetensch. Proc. Ser. A 53:386-392 (Part I), 53:521-525 (Part II), 53:1397-1412 (Part III).

Sen, P.K. (1968) Estimates of Regression Coefficient Based on Kendall's tau. Journal of the American Statistical Association. 63(324):1379-1389.

Siegel, A.F. (1982) Robust Regression Using Repeated Medians. Biometrika, 69(1):242-244

See Also

kendallTrendTest for model details

overlay for available ... arguments

Examples

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## Not run: 
 library(raster)
 r.logo <- stack(system.file("external/rlogo.grd", package="raster"),
                 system.file("external/rlogo.grd", package="raster"),
 			    system.file("external/rlogo.grd", package="raster")) 
 
 # Calculate trend slope with p-value and confidence level(s)
 logo.trend <- raster.kendall(r.logo, p.value=TRUE, confidence=TRUE)
   names(logo.trend) <- c("slope","p.value","LCI","UCI")
     plot(logo.trend)

## End(Not run)

jeffreyevans/spatialEco documentation built on Oct. 13, 2018, 6:53 p.m.