Feature: GWPCA

NAMESPACE

@@ -8,6 +8,7 @@ S3method(fitted,gtdrm)
 S3method(fitted,gwlcrm)
 S3method(fitted,gwrm)
 S3method(fitted,gwrmultiscalem)
+S3method(glyph.plot,gwpcam)
 S3method(plot,gtdrm)
 S3method(plot,gwcorrm)
 S3method(plot,gwlcrm)
@@ -19,6 +20,7 @@ S3method(print,gtdrm)
 S3method(print,gwavgm)
 S3method(print,gwcorrm)
 S3method(print,gwlcrm)
+S3method(print,gwpcam)
 S3method(print,gwrm)
 S3method(print,gwrmultiscalem)
 S3method(residuals,gtdrm)
@@ -28,11 +30,13 @@ S3method(residuals,gwrmultiscalem)
 S3method(step,default)
 S3method(step,gtdrm)
 S3method(step,gwrm)
+export(glyph.plot)
 export(gtdr)
 export(gtdr_config)
 export(gwaverage)
 export(gwcorr_config)
 export(gwcorrelation)
+export(gwpca)
 export(gwr_basic)
 export(gwr_lcr)
 export(gwr_multiscale)

R/RcppExports.R

@@ -13,6 +13,10 @@ gw_correlation_cal <- function(x1, x2, coords, bw, adaptive, kernel, longlat, p,
     .Call(`_GWmodel3_gw_correlation_cal`, x1, x2, coords, bw, adaptive, kernel, longlat, p, theta, initial_type, optim_bw_criterion, parallel_type, parallel_arg, variable_names, verbose)
 }
 
+gwpca_cal <- function(x, coords, bw, adaptive, kernel, longlat, p, theta, keep_components) {
+    .Call(`_GWmodel3_gwpca_cal`, x, coords, bw, adaptive, kernel, longlat, p, theta, keep_components)
+}
+
 gwr_basic_fit <- function(x, y, coords, bw, adaptive, kernel, longlat, p, theta, optim_bw_lower, optim_bw_upper, hatmatrix, intercept, parallel_type, parallel_arg, optim_bw, optim_bw_criterion, select_model, select_model_criterion, select_model_threshold, variable_names, verbose) {
     .Call(`_GWmodel3_gwr_basic_fit`, x, y, coords, bw, adaptive, kernel, longlat, p, theta, optim_bw_lower, optim_bw_upper, hatmatrix, intercept, parallel_type, parallel_arg, optim_bw, optim_bw_criterion, select_model, select_model_criterion, select_model_threshold, variable_names, verbose)
 }

R/gwpca.R

@@ -0,0 +1,262 @@
+#' Calibrate a GWPCA model
+#'
+#' @param formula Regresison model.
+#' @param data A `sf` objects.
+#' @param bw Should provide a value to set the size of bandwidth,
+#' @param adaptive Whether the bandwidth value is adaptive or not.
+#' @param kernel Kernel function used.
+#' @param longlat Whether the coordinates
+#' @param p Power of the Minkowski distance,
+#'  default to 2, i.e., Euclidean distance.
+#' @param theta Angle in radian to roate the coordinate system, default to 0.
+#' @param components How many components want to keep, default to 2.
+#' @param scale Whether to standardised data.
+#' 
+#' @return A `gwpcam` object.
+#'
+#' @examples
+#' data(LondonHP)
+#'
+#' # Basic usage
+#' gwpca(~FLOORSZ + UNEMPLOY + PROF, LondonHP, 50, TRUE, components = 2)
+#' 
+#' # Standardised
+#' m <- gwpca(~FLOORSZ + UNEMPLOY + PROF, LondonHP, 50, TRUE, components = 2, scale = TRUE)
+#' # Plot local loadings
+#' glyph.plot(m)
+#' @seealso glyph.plot
+#'
+#' @importFrom stats na.action model.frame model.extract model.matrix terms
+#' @export
+gwpca <- function(
+    formula,
+    data,
+    bw = NA,
+    adaptive = FALSE,
+    kernel = c("gaussian", "exp", "bisquare", "tricube", "boxcar"),
+    longlat = FALSE,
+    p = 2.0,
+    theta = 0.0,
+    components = 2,
+    scale = FALSE
+) {
+    ### Check args
+    kernel = match.arg(kernel)
+    attr(data, "na.action") <- getOption("na.action")
+
+    ### Extract coords
+    data <- do.call(na.action(data), args = list(data))
+    coords <- as.matrix(sf::st_coordinates(sf::st_centroid(data)))
+    if (is.null(coords) || nrow(coords) != nrow(data))
+        stop("Missing coordinates.")
+
+    ### Extract variables
+    mc <- match.call(expand.dots = FALSE)
+
+    mf <- model.frame(formula = formula(update(formula, ~ . - 1)), data = sf::st_drop_geometry(data))
+    mt <- attr(mf, "terms")
+    x <- model.matrix(mt, mf)
+    if(scale)  x <- scale(x)
+    indep_vars <- colnames(x)
+
+    ### Check whether bandwidth is valid.
+    if (missing(bw)) {
+        stop("Please input bandwidth!")
+    }
+    if (!(is.numeric(bw) || is.integer(bw))) {
+        stop("Please input correct bandwidth!")
+    }
+
+    components <- as.integer(floor(components))
+    if (components < 1) {
+        stop("Components must be an interger greater than 0 !!")
+    }
+    if(length(indep_vars) < components) {
+        stop("Components to keep must be lower than variable counts!")
+    }
+
+
+    c_result <- tryCatch(gwpca_cal(
+        x, coords,
+        bw, adaptive, enum(kernel), longlat, p, theta,
+        components
+    ), error = function(e) {
+        stop("Error:", conditionMessage(e))
+    })
+
+    local_loadings <- c_result$local_loadings
+    # local_scores <- c_result$local_scores
+
+    local_PV <- c_result$local_PV
+
+    pc_names <- paste0("PC", seq_len(components), "_PV")
+    colnames(local_PV) <- pc_names
+    sdf_data <- as.data.frame(local_PV)
+    sdf_data$geometry <- sf::st_geometry(data)
+    sdf <- sf::st_sf(sdf_data)
+
+    ### Return result
+    gwpcam <- list(
+        SDF = sdf,
+        local_loadings = local_loadings,
+        # local_scores = local_scores,
+        args = list(
+            x = x,
+            coords = coords,
+            bw = bw,
+            adaptive = adaptive,
+            kernel = kernel,
+            longlat = longlat,
+            p = p,
+            theta = theta,
+            keep_components = components
+        ),
+        call = mc,
+        indep_vars = indep_vars
+    )
+    class(gwpcam) <- "gwpcam"
+    gwpcam
+}
+
+#' Print description of a `gwpcam` object
+#'
+#' @param x An `gwpcam` object returned by [gwpca()].
+#' @param decimal_fmt The format string passing to [base::sprintf()].
+#' @inheritDotParams print_table_md
+#'
+#' @method print gwpcam
+#' @importFrom stats coef fivenum
+#' @rdname print
+#' @export
+print.gwpcam <- function(x, decimal_fmt = "%.3f", ...) {
+    if (!inherits(x, "gwpcam")) {
+        stop("It's not a gwpcam object.")
+    }
+
+    ### Basic Information
+    cat("Geographically Weighted Principal Component Analysis", fill = T)
+    cat("========================================", fill = T)
+    cat("  Formula:", deparse(x$call$formula), fill = T)
+    cat("     Data:", deparse(x$call$data), fill = T)
+    cat("   Kernel:", x$args$kernel, fill = T)
+    cat("Bandwidth:", x$args$bw, ifelse(x$args$adaptive, "(Nearest Neighbours)", "(Meters)"), fill = T)
+    cat("   Keep components:", x$args$keep_components, fill = T)
+    cat("\n", fill = T)
+
+    cat("Summary of Local PV", fill = T)
+    cat("--------------------------------", fill = T)
+    local_PV <- sf::st_drop_geometry(x$SDF)
+    local_PV_fivenum <- t(apply(local_PV, 2, fivenum))
+    colnames(local_PV_fivenum) <- c("Min.", "1st Qu.", "Median", "3rd Qu.", "Max.")
+    rownames(local_PV_fivenum) <- colnames(local_PV)
+    loadings_1st_str <- rbind(
+        c("Local loadings", colnames(local_PV_fivenum)),
+        cbind(rownames(local_PV_fivenum), matrix2char(local_PV_fivenum, decimal_fmt))
+    )
+    print_table_md(loadings_1st_str, ...)
+    cat("\n", fill = T)
+
+    cat("Summary of Local Loadings in PC1", fill = T)
+    cat("--------------------------------", fill = T)
+    loadings_1st <- x$local_loadings[, , 1]
+    loadings_1st_fivenum <- t(apply(loadings_1st, 2, fivenum))
+    colnames(loadings_1st_fivenum) <- c("Min.", "1st Qu.", "Median", "3rd Qu.", "Max.")
+    rownames(loadings_1st_fivenum) <- x$indep_vars
+    loadings_1st_str <- rbind(
+        c("Local loadings", colnames(loadings_1st_fivenum)),
+        cbind(rownames(loadings_1st_fivenum), matrix2char(loadings_1st_fivenum, decimal_fmt))
+    )
+    print_table_md(loadings_1st_str, ...)
+    cat("\n", fill = T)
+}
+
+#' Glyph plot generic
+#' @export
+glyph.plot <- function(x, ...) {
+    UseMethod("glyph.plot")
+}
+
+#' Glyph plot for local loadings in PC1 of GWPCA model.
+#'
+#' @param x A "gwpcam" object.
+#' @param y Ignored.
+#' @param columns Column names to plot.
+#'  If it is missing or non-character value, all coefficient columns are plotted.
+#' @param sign whether to plot according to the loadings is beyond 0 or not.
+#' @param \dots Additional arguments passed to [sf::plot()].
+#' @method glyph.plot gwpcam
+#' @export
+glyph.plot.gwpcam <- function(x, y, ..., columns, sign = FALSE) {
+    if (!inherits(x, "gwpcam")) {
+        stop("It's not a gwpcam object.")
+    }
+
+    sdf <- sf::st_as_sf(x$SDF)
+    coords <- sf::st_coordinates(sdf)
+    r <- 0.05 * max(diff(range(coords[, 1])), diff(range(coords[, 2])))
+
+    ld <- x$local_loadings[, , 1]
+    colnames(ld) <- x$indep_vars
+    n.col <- ncol(ld)
+
+    colors <- rainbow(n.col)
+    rgb_colors <- col2rgb(colors) / 255
+
+    rowmax <- function(z) z[cbind(1:nrow(z), max.col(abs(z)))]
+    ld <- sweep(ld, 1, sign(rowmax(ld)), "*")
+
+    angles <- (0:(n.col - 1)) * 2 * pi / n.col
+    J <- 0 + (0 + 1i)
+    disp <- exp((pi / 2 - angles) * J) * r
+    loc2 <- coords[, 1] + coords[, 2] * J
+    ld.max <- max(ld)
+    ld.scaled <- abs(ld) / ld.max
+
+    plot(coords, asp = 1, type = "n")
+    points(coords, pch = 14, cex = 0.1, col = "black")
+
+    for (i in 1:nrow(ld)) {
+        for (j in 1:ncol(ld)) {
+        l.from <- loc2[i]
+        l.to <- loc2[i] + disp[j] * ld.scaled[i, j]
+
+    if (sign) {
+    alpha <- 1
+    col <- if (ld[i, j] > 0) {
+        rgb(1, 0, 0, alpha)  # red
+    } else {
+        rgb(0, 0, 1, alpha)  # blue
+    }
+    } else {
+            col_index <- (j - 1) %% n.col + 1
+            col <- rgb(rgb_colors[1, col_index],
+                    rgb_colors[2, col_index],
+                    rgb_colors[3, col_index],
+                    alpha = 1)
+        }
+
+        lines(Re(c(l.from, l.to)), Im(c(l.from, l.to)), col = col)
+        }
+    }
+
+    par(cex = 1.3)
+    legend_labels <- colnames(ld)
+
+    if (!sign) {
+        text.w <- max(strwidth(legend_labels)) * 1.2
+        legend("bottomleft",
+            legend = legend_labels,
+            col = colors,
+            lty = 1,
+            lwd = 2,
+            text.width = text.w,
+            bg = "white")
+    } else {
+        legend("bottomleft",
+            legend = c("Positive loading", "Negative loading"),
+            col = c("red", "blue"),
+            lty = 1,
+            lwd = 2,
+            bg = "white")
+    }
+}