1. 使用polygon进行纯色填充

# polygon函数介绍polygon(x, y = NULL, density = NULL, angle = 45, border = NULL, col = NA, lty = par("lty"), ..., fillOddEven = FALSE)其中density为填充的阴影线的密度，angle为阴影线的斜率(角度)。值得注意的是，当你需要纯色填充时，density和angle可以忽略不写。然后border为边框的颜色。同时border也可以是逻辑。即FALSE相当于NULL，TRUE相当于为前景色。# Distance Between Brownian Motions 布朗运动之间的距离n <- 100xx <- c(0:n, n:0) #生成202个元素的向量，其中前面101与后面101数字对称yy <- c(c(0, cumsum(stats::rnorm(n))), rev(c(0, cumsum(stats::rnorm(n)))))plot (xx, yy, type = "n", xlab = "Time", ylab = "Distance")polygon(xx, yy, col = "gray", border = "red")title("布朗运动之间的距离")

如图 两个布朗运动间的距离用灰色填充

2. 使用polygon进行阴影线填充

# Line-shaded polygons 线阴影多边形plot(c(1, 9), 1:2, type = "n")polygon(1:9, c(2,1,2,1,NA,2,1,2,1), density = c(10, 20), angle = c(-45, 45)) #density的值为两个，即不同的密度

补充：R语言世界地图转为SpatialPolygons以及去除地图内国家边界

##加载包

library(maps)library(maptools)library(ggplot2)library(metR)

##提取地图并转换为Spatialpolygons

loc <- maps::map('world',interior = FALSE, plot = FALSE, fill = TRUE,col = 'transparent')ids <- sapply(strsplit(loc$names, ":"), function(x) x[1])loc <- map2SpatialPolygons(map = loc, IDs = ids,proj4string = CRS('+proj=longlat +datum=WGS84 +no_defs'))

##去除内边界

worldmap1 <- unionSpatialPolygons(loc, IDs = rep(1,length(loc)))

##画图

worldmap2 <- fortify(worldmap1)ggplot()+ scale_x_longitude(expand = c(0, 0), breaks = seq(-180, 180, 45))+ scale_y_latitude(expand = c(0, 0), breaks = seq(-90, 90, 30))+ geom_polygon(data = worldmap2, mapping = aes(x = long, y = lat, group = group), colour = 'gray', fill = 'gray', size = 0.5)

##结果图

以上为个人经验，希望能给大家一个参考，也希望大家多多支持。如有错误或未考虑完全的地方，望不吝赐教。