R/graphPolygonWithGradient.R

In kendonB/bellmisc: What the package does (short line)

#' @export
#' @title
#' Plot a polygon with colour fill over a polygon with black lines.
#' @description
#' Plot a polygon with colour fill over a polygon with black lines.
#' @param colourVar numeric variable that defines the gradient
#'   colour. Same length and order as dataPoly.
#' @param dataPoly SpatialPolygonsDataFrame to be plotted.
#' @param fileName filename (not with directory or extension) as character.
#' @param legendTitle legend title as character.
#' @param directoryPlots directory to store plots
#' @param backPolygon optional background polygon to be
#' plotted on top of - fortified or raw (prefortifying will be faster if
#' several maps are being generated).
#' @param brewerPalette brewer palette name as character. Default is "Spectral".
#' @param rev logical to indicate if Brewer colours should be reversed.
#' @return a ggplot2 object
graphPolygonWithGradient <- function(colourVar, dataPoly,
                                               legendTitle, fileName, plotTitle,
                                               directoryPlots=getwd(),
                                               backPolygon=NULL, brewerPalette="RdYlGn",
                                               fontFam = NULL,
                                               myrev=TRUE,
                                               limits=NULL,
                                               heightAdj = 1,
                                               widthAdj = 1){
  if (is.null(limits)) {
    limits <- c(min(colourVar, na.rm=TRUE), max(colourVar, na.rm=TRUE))
  }
  
  dataPoly$tmpColour <- colourVar
  if (!is.null(backPolygon) & !(class(backPolygon) == "data.frame")) {
    backPolygon <- convertShpPolyToDf(backPolygon)
  }
  
  if (!(class(dataPoly) == "data.frame")) {
    dataPoly <- convertShpPolyToDf(dataPoly)
  }
  
  plotMap <- ggplot(dataPoly, aes(x=long, y=lat, group=group))+
    geom_polygon(aes(fill=tmpColour))+
    geom_polygon(data = backPolygon, aes(group = group), alpha = 1, colour = "black", fill = NA)
  
  # 
  if (!is.null(limits)){
    if (limits[1] < 0 & limits[2] > 0) {
      # Get the middle one
      tmp <- rescale(c(limits[1], 0, limits[2]))[2]
      values <- c(rescale(seq(limits[1], 0, length.out = 5),to = c(0, tmp)),
                  rescale(seq(0, limits[2], length.out = 5),to = c(tmp, 1)))
      values <- values[-5]
    } else {
      # The range doesn't cover zero so just use the top/bottom half
      values <- seq(-1, 1, length.out = 9)
    }
  } 
  
  if (myrev){
    plotMap <- plotMap + scale_fill_gradientn(legendTitle, na.value = NA, limits=limits,
                                              colours=rev(brewer.pal(9,brewerPalette)),
                                              values=values)
  } else {
    plotMap <- plotMap + scale_fill_gradientn(legendTitle, na.value = NA, limits=limits,
                                              colours=brewer.pal(9,brewerPalette),
                                              values=values)
  }
  
  plotMap <- plotMap + theme(axis.text=element_blank(), 
                             axis.ticks=element_blank(),
                             axis.title=element_blank(),
                             panel.grid.major = element_blank(),
                             panel.grid.minor = element_blank(),
                             panel.background = element_blank(),
                             panel.margin = unit(c(0,0,0,0),"cm"),
                             plot.margin=unit(c(0,0,-0.5,0),"cm")) +
    theme(plot.title=element_text(size=20, family = fontFam)) +
    theme(legend.title=element_text(size=16, family = fontFam)) +
    ggtitle(plotTitle) +
    scale_x_continuous(limits = c(-124.5, -114)) +
    coord_fixed(ylim = c(32.5, 42.5))
  
  fileName1 <- paste0(file.path(directoryPlots, fileName), ".pdf")
  ggsave(filename = fileName1, plot = plotMap, width = 12, height = 6)
  fileName2 <- paste0(file.path(directoryPlots, fileName), ".png")
  ggsave(filename = fileName2, plot = plotMap, width = 12, height = 6, dpi = 72)
  fileName3 <- paste0(file.path(directoryPlots, fileName), ".jpg")
  ggsave(filename = fileName3, plot = plotMap, width = 12, height = 6, dpi = 144)
  return(plotMap)
}