PROGRAM

mwcor.R
 

USE

Calculates a bivariate moving window correlation on two rasters​

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REQUIRES

R >= 2.14, sp, spdep
         

ARGUMENTS
  x      X VARIABLE GRID OBJECT 
  y      Y VARIABLE GRID OBJECT
  dist   WINDOW SIZE IN DISTANCE UNITS (DEFAULT IS "AUTO" AND IS CALCULATED AUTOMATICLY)
  ...    ADDITIONAL ARGUMENTS TO PASS TO cor FUNCTION

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VALUE
  A SpatialGridDataFrame sp OBJECT WITH THE CORRLEATIONS

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EXAMPLES
  library(gstat)                                        
  library(sp)                                           
  library(spdep)                                        
                                                        
  data(meuse)                                           
  data(meuse.grid)                                      
  coordinates(meuse) <- ~x + y                          
  coordinates(meuse.grid) <- ~x + y                     
                                                        
  # GRID-1 log(copper):                                             
  v1 <- variogram(log(copper) ~ 1, meuse)                 
  x1 <- fit.variogram(v1, vgm(1, "Sph", 800, 1))          
   G1 <- krige(zinc ~ 1, meuse, meuse.grid, x1, nmax = 30)
    gridded(G1) <- TRUE                                     
     G1@data = as.data.frame(G1@data[,-2])
 
  # GRID-2 log(lead):                                             
  v2 <- variogram(log(lead) ~ 1, meuse)                 
  x2 <- fit.variogram(v2, vgm(.1, "Sph", 1000, .6))       
   G2 <- krige(zinc ~ 1, meuse, meuse.grid, x2, nmax = 30)
    gridded(G2) <- TRUE   
     G2@data <- as.data.frame(G2@data[,-2])
 
 # MOVING WINDOW CORRELATION AND PLOT RESULTS
  gcorr <- mwcor(G1, G2, 40, method="spearman")
    colr=colorRampPalette(c("blue", "yellow", "red"))
      spplot(gcorr, col.regions=colr(100))