# R code to plot latitudinal profiles of (circular) mean aspect, along

# with both RMSE and (circular) correlation coefficients comparing fused

# layers with both the raw ASTER and with the Canada DEM

#

# Aspect layers were generated from the respect DEMs in this way:

#   $ gdaldem aspect -s 111120 <layer>.tif <layer>_a.tif

# ...where the default azimuthal behavior produces output values ranging

# from 0-360 where 0 is north, and proceeding clockwise

#

# For exploratory plotting, note the following (uses 'circular'

# package):

#  > cx <- circular(as.matrix(a.bg)[151,], units="degrees",

#      rotation="clock", zero=pi/2)

#  > rose.diag(cx, bins=8)

#  > points(mean.circular(cx, na.rm=TRUE), col="red")

#

#

# The results (plots) are saved at 

#   "/data/project/organisms/DEM?Yuni/documents/aspect"

#

# Original author: Jim Regetz

# [13-JUL-2011]

#   Edits by Yuina to auto-apply for nine regions.

#   

#   9-Dec-2011

#   Yuina Nunokawa

library(raster)

library(circular)

# load aspecct rasters

aster.dir      <- "/data/project/organisms/DEM/Yuni/Data/aster2"

srtm.dir       <- "/data/project/organisms/DEM/Yuni/Data/srtm"

aster.straddle <- list.files(aster.dir, pattern="^aster2.*_straddle_a.tif")

srtm.below     <- list.files(srtm.dir, pattern="^srtm_.*_below_a.tif") 

fused.straddle <- list.files(aster.dir, pattern="^fused.*_straddle_a.tif")

fused.bgau     <- list.files(aster.dir, pattern="^fused.*_blendgau_a.tif")

# simple helper function to calculate row-wise means using circular

# mean, patterned after circ.mean in the CircStats package

rowMeansC <- function(r1, na.rm=TRUE) {

    m1 <- as.matrix(r1)

    m1[] <- (m1 * pi)/180

    sinr <- rowSums(sin(m1), na.rm=na.rm)

    cosr <- rowSums(cos(m1), na.rm=na.rm)

    cmeans <- atan2(sinr, cosr)

    (cmeans * 180)/pi

}

aspect <- function(a.aster2, a.srtm, a.uncor, a.bg, file.name, aster.dir, srtm.dir){

        # extract raster latitudes for later

        lats2400 <- yFromRow(a.aster2, 1:nrow(a.aster2))

        lats1200 <- yFromRow(a.srtm, 1:nrow(a.srtm))

        # initialize output pdf device driver

        name <- paste("aspect_", file.name, ".pdf", sep="") 

        pdf(file.path("/data/project/organisms/DEM/Yuni/documents/aspect", file=name), height=8, width=11.5)

        #

        # plot latitudinal profiles of mean aspect

        #

        par(mfrow=c(2,2), omi=c(1,1,1,1))

        ylim <- c(-180, 180)

        plot(lats2400, rowMeansC(a.aster2), type="l", xlab="Latitude", ylab="Mean aspect", ylim=ylim)

        axis(2, at=c(-180, -90, 0, 90, 180), labels=c("S", "W", "N", "E", "S"))

        lines(lats1200, rowMeans(as.matrix(a.srtm), na.rm=TRUE), col="red")

        text(min(lats2400), max(ylim)+0.5, pos=4, font=3, labels="Original")

        legend("topright", legend=c("ASTER2", "SRTM"), col=c("blue", "red"), lty=c(1, 1), bty="n")

        abline(v=60, col="red", lty=2)

        mtext(expression(paste("Latitudinal profiles of mean aspect", file.name)), adj=0, line=2, font=2)

        plot(lats2400, rowMeansC(a.uncor), type="l", xlab="Latitude", ylab="Mean aspect", ylim=ylim)

        axis(2, at=c(-180, -90, 0, 90, 180), labels=c("S", "W", "N", "E", "S"))

        legend("topright", legend=c("ASTER2"), col=c("black"), lty=c(1, 1), bty="n")

        text(min(lats2400), max(ylim)+0.5, pos=4, font=3, labels="simple fused")

        abline(v=60, col="red", lty=2)

        plot(lats2400, rowMeansC(a.bg), type="l", xlab="Latitude", ylab="Mean aspect", ylim=ylim)

        legend("topright", legend=c("ASTER2"), col=c("black"), lty=c(1, 1), bty="n")

        text(min(lats2400), max(ylim)+0.5, pos=4, font=3, labels="gaussian blend")

        abline(v=60, col="red", lty=2)

        dev.off () 

}

num.regions <- 9

plotAspect <-lapply(1:num.regions, function(region, aster.dir, srtm.dir){

    a.aster2 <- raster(file.path(aster.dir, aster.straddle[region])) 

    a.srtm <- raster(file.path(srtm.dir, srtm.below[region]))  

    a.uncor <- raster(file.path(aster.dir, fused.straddle[region]))

    a.bg <- raster(file.path(aster.dir, fused.bgau[region])) 

    file.name <- substr(srtm.below[region], 6, 13)

    aspect(a.aster2, a.srtm, a.uncor, a.bg, file.name, aster.dir, srtm.dir)

}, aster.dir=aster.dir, srtm.dir=srtm.dir)