lattice levelplot 或 ggplot2 map R 的自定义图例

Posted 2023-02-16

【中文标题】lattice levelplot 或 ggplot2 map R 的自定义图例

【英文标题】：Custom legend for lattice levelplot or ggplot2 map R

【发布时间】：2018-07-29 01:29:09

【问题描述】：

鉴于以下code、map 和sample data： 而不是在地图上绘制watersheds 等的名称，如何使用ggplot2 或levelplot 生成单独的图例，就像使用ArcGIS? 一样基本上，我想生成这张地图上显示的图例最好是levelplot或ggplot2。

Code 和 map 以及用于在R 中绘图的示例数据。

require(colorRamps)
require(raster)
require(rasterVis)
require(mapproj)
library(raster)    
library(proj4)


# Get province borders and project it to same CRS than raster
can1 <- getData('GADM', country="CAN", level=1)
getData('ISO3') # country name
dem=getData('alt', country='CAN', mask=TRUE)


require( colorRamps )
my.at <- unique(round(seq(ceiling(5800), floor(1), length.out = 51),0))#at: numeric vector specifying where the colors change. must be of length 1 more than the col vector.

myColorkey <- list(at=my.at,space = "bottom", tck = c(0,0),## where the colors change 
                   labels=list(axis.line = list(col = NA),at=myat1,rot=0,cex=1.4,font=1,
                               fontface=1),height=0.99,width=1.8)

col<-colorRampPalette(c("#d9d9d9", "#bdbdbd", "#969696", "#737373", "#525252", "#252525", "#000000"))


levelplot(dem,maxpixel=ncell(dem),panel=panel.levelplot.raster,names.attr=names(dem),
          interpolate=F,margin=FALSE,xlab=list(label="Longitude",cex=1.5),yscale.components = yscale.raster.subticks,
          xscale.components = xscale.raster.subticks,
          ylab=list(label="Latitude",cex=1.5),
          par.strip.text=list(cex=1),xlim=c(-158, -48.99485),
          ylim=c(38.00513, 85),col.regions=col,at = seq(0, 5800,100),
          colorkey = list(space = "bottom", labels = list(at = seq(0, 5800,800), rot=0,cex=1.1,font=6,fontface=1,
                                                          labels =c("0",  "800", "1600", "2400", "3200", "4000", "4800", "5600")),
                          height=0.99,width=1.8,tck = c(0,0)),
          par.settings=list(panel.background=list(col="white"),axis.line=list(lwd=1.9), strip.border=list(lwd=1.9),layout.heights=list(xlab.key.padding=-0.2)),
          cex=0.8, scales = list(x=list(draw=TRUE,cex=1.2), y=list(draw=TRUE,cex=1.2)))+
 layer(sp.polygons(can1,lwd=0.5,col="gray40"))+
 layer(sp.polygons(watershed,lwd=1,col=c("#a6cee3", "#1f78b4", "#b2df8a", "#33a02c", "#fb9a99", "#e31a1c", "#fdbf6f", "#ff7f00"),
                   fill=c("#a6cee3", "#1f78b4", "#b2df8a", "#33a02c", "#fb9a99", "#e31a1c", "#fdbf6f", "#ff7f00")))+
 layer(sp.polygons(lake,lwd=1,col="cadetblue1",fill="cadetblue1"))+
 layer(sp.lines(river,lwd=0.5,col="blue4"))+
 layer(sp.text(coordinates(watershed), txt = watershed$NAMRB_EN, pos =c(1,1,3,3,1,4,1,1),col="black",font=list(face="bold"),cex=0.8))

【问题讨论】：

myat1 未分配。

地图的用途是什么？当我对高程感兴趣时，我会尝试摆脱填充颜色的多边形，并仅绘制每个分水岭的边界。例如，ArcGIS 地图中的哥伦比亚分水岭完全破坏了高程信息。

【参考方案1】：

您可以尝试将您的代码调整为this example，以便为分水岭和高程添加图例：

library(sp) 
library(raster) 
library(rasterVis) 

f <- system.file("external/test.grd", package="raster") 
r <- raster(f) 

data(meuse) 
coordinates(meuse) = c("x", "y") 
meuse$class <- cut(meuse$zinc, 3) 

ptsCols <- c('black', 'red', 'blue') 

lvp <- levelplot(r, margin = FALSE, 
                 ## Define the legend for the spplot graphic 
                 key = list(space = 'top', text = list(levels(meuse$class)), 
                     points = list(pch = 21, fill = ptsCols)), 
                 ## Legend for the Raster object 
                 colorkey=list(space="right",width=0.75,height=0.75)) 

spp <- spplot(meuse["class"], col.regions = ptsCols) 

lvp + spp 

【讨论】：

谢谢@Christpher。传说中的湖泊河流呢？