integrate descTools Cohen's Kappa directly in package

add suggest mardown as it is not a hard dep of knitr anymore

DESCRIPTION

@@ -29,7 +29,8 @@ Suggests:
     knitr,
     rmarkdown,
     testthat (>= 3.0.0),
-    png
+    png,
+    markdown
 Config/testthat/edition: 3
 VignetteBuilder: knitr
 LazyData: true

NAMESPACE

@@ -1,5 +1,6 @@
 # Generated by roxygen2: do not edit by hand
 
+export(CohenKappa)
 export(LCZareas)
 export(areColors)
 export(compareLCZ)
@@ -36,7 +37,9 @@ importFrom(ggplot2,ggtitle)
 importFrom(ggplot2,guides)
 importFrom(grDevices,palette.colors)
 importFrom(magrittr,"%>%")
+importFrom(stats,qnorm)
 importFrom(stats,quantile)
 importFrom(terra,as.polygons)
 importFrom(terra,crop)
 importFrom(terra,rast)
+importFrom(tidyr,drop_na)

R/CohenKappa.R

@@ -0,0 +1,126 @@
+#' Compute Cohen's Kappa Coefficient. Taken from descTools,
+#' who based it on Kappa from library(vcd)
+#' author: David Meyer
+#' see also: kappa in library(psych)
+#' Integrated here to reduce dependecy to descTools as it is the only function from DescTools we used
+#' Computes the agreement rates Cohen's kappa and weighted kappa and their confidence intervals.
+#'
+#' @param x can either be a numeric vector or a confusion matrix. 
+#' In the latter case x must be a square matrix, in lczexplore, 
+#' will take the matrix of agreement weighted by area for all intersected geometries
+#' @param y not used here, but allows to compute cross table of x and y as an entry
+#' @param weights either one out of \code{"Unweighted"} (default), \code{"Equal-Spacing"}, 
+#' \code{"Fleiss-Cohen"}, which will calculate the weights accordingly, 
+#' or a user-specified matrix having the same dimensions as x containing the weights for each cell.
+#' @param conf.level confidence level of the interval. 
+#' If set to \code{NA} (which is the default) no confidence intervals will be calculated.
+#' @param \dots further arguments are passed to the function \code{\link{table}}, 
+#' allowing i.e. to set \code{useNA}. This refers only to the vector interface.
+#' @importFrom stats qnorm
+#' @details Cohen's kappa is the diagonal sum of the (possibly weighted) relative frequencies, corrected for expected values and standardized by its maximum value. \cr
+#' The equal-spacing weights (see Cicchetti and Allison 1971) are defined by \deqn{1 - \frac{|i - j|}{r - 1}}
+#' \code{r} being the number of columns/rows, and the Fleiss-Cohen weights by \deqn{1 - \frac{(i - j)^2}{(r - 1)^2}}
+#' The latter attaches greater importance to closer disagreements
+#' @references Cohen, J. (1960) A coefficient of agreement for nominal scales. \emph{Educational and Psychological Measurement}, 20, 37-46.
+#' Everitt, B.S. (1968), Moments of statistics kappa and weighted kappa. \emph{The British Journal of Mathematical and Statistical Psychology}, 21, 97-103.
+#' Fleiss, J.L., Cohen, J., and Everitt, B.S. (1969), Large sample standard errors of kappa and weighted kappa. \emph{Psychological Bulletin}, 72, 332-327.
+#' Cicchetti, D.V., Allison, T. (1971) A New Procedure for Assessing Reliability
+#' of Scoring EEG Sleep Recordings \emph{American Journal of EEG Technology}, 11, 101-109.
+#' @author David Meyer <[email protected]>, some changes and tweaks Andri Signorell <[email protected]> and
+#' integrated for areas by Matthieu Gousseff
+#' @return the value of this pseudoKappa
+#' @export  
+#'
+#' @examples 
+#' # from Bortz et. al (1990) Verteilungsfreie Methoden in der Biostatistik, Springer, pp. 459
+#' m <- matrix(c(53,  5, 2,
+#'              11, 14, 5,
+#'              1,  6, 3), nrow=3, byrow=TRUE,
+#'            dimnames = list(rater1 = c("V","N","P"), rater2 = c("V","N","P")) )
+#' # confusion matrix interface
+#' CohenKappa(m, weight="Unweighted")
+CohenKappa <- function (x, y = NULL,
+                        weights = c("Unweighted", "Equal-Spacing", "Fleiss-Cohen"),
+                        conf.level = NA, ...) {
+
+  if (is.character(weights))
+    weights <- match.arg(weights)
+
+  if (!is.null(y)) {
+    # we can not ensure a reliable weighted kappa for 2 factors with different levels
+    # so refuse trying it... (unweighted is no problem)
+
+    if (!identical(weights, "Unweighted"))
+      stop("Vector interface for weighted Kappa is not supported. Provide confusion matrix.")
+
+    # x and y must have the same levels in order to build a symmetric confusion matrix
+    x <- factor(x)
+    y <- factor(y)
+    lvl <- unique(c(levels(x), levels(y)))
+    x <- factor(x, levels = lvl)
+    y <- factor(y, levels = lvl)
+    x <- table(x, y, ...)
+
+  } else {
+    d <- dim(x)
+    if (d[1L] != d[2L])
+      stop("x must be square matrix if provided as confusion matrix")
+  }
+
+  d <- diag(x)
+  n <- sum(x)
+  nc <- ncol(x)
+  colFreqs <- colSums(x)/n
+  rowFreqs <- rowSums(x)/n
+
+  kappa <- function(po, pc) {
+    (po - pc)/(1 - pc)
+  }
+
+  std <- function(p, pc, k, W = diag(1, ncol = nc, nrow = nc)) {
+    sqrt((sum(p * sweep(sweep(W, 1, W %*% colSums(p) * (1 - k)),
+                        2, W %*% rowSums(p) * (1 - k))^2) -
+      (k - pc * (1 - k))^2) / crossprod(1 - pc)/n)
+  }
+
+  if(identical(weights, "Unweighted")) {
+    po <- sum(d)/n
+    pc <- as.vector(crossprod(colFreqs, rowFreqs))
+    k <- kappa(po, pc)
+    s <- as.vector(std(x/n, pc, k))
+
+  } else {
+
+    # some kind of weights defined
+    W <- if (is.matrix(weights))
+      weights
+    else if (weights == "Equal-Spacing")
+      1 - abs(outer(1:nc, 1:nc, "-"))/(nc - 1)
+    else # weights == "Fleiss-Cohen"
+      1 - (abs(outer(1:nc, 1:nc, "-"))/(nc - 1))^2
+
+    po <- sum(W * x)/n
+    pc <- sum(W * colFreqs %o% rowFreqs)
+    k <- kappa(po, pc)
+    s <- as.vector(std(x/n, pc, k, W))
+  }
+
+  if (is.na(conf.level)) {
+    res <- k
+  } else {
+    ci <- k + c(1, -1) * qnorm((1 - conf.level)/2) * s
+    res <- c(kappa = k, lwr.ci = ci[1], upr.ci = ci[2])
+  }
+
+  return(res)
+
+}
+
+
+
+# KappaTest <- function(x, weights = c("Equal-Spacing", "Fleiss-Cohen"), conf.level = NA) {
+# to do, idea is to implement a Kappa test for H0: kappa = 0 as in
+# http://support.sas.com/documentation/cdl/en/statugfreq/63124/PDF/default/statugfreq.pdf, pp. 1687
+#   print( "still to do...." )
+
+# }

R/compareLCZ.R

@@ -386,8 +386,9 @@ matConfLarge<-as.matrix(matConfLarge)
 
 # Add pseudo Kappa Statistic to output to   
 PseudoWeightedCross<-matConfLarge*100
-pseudoK<-DescTools::CohenKappa(x=PseudoWeightedCross)  
-matConfOut$pseudoK<-pseudoK
+# pseudoK<-DescTools::CohenKappa(x=PseudoWeightedCross)  
+  pseudoK<-CohenKappa(x=PseudoWeightedCross)
+  matConfOut$pseudoK<-pseudoK
 
 areas<-matConfOut$areas
 percAgg<-matConfOut$percAgg