r - 调整ggplot2中图例键周围边框的粗细

Question

我正在绘制一张新西兰地图，不同地区的颜色不同。这是我的代码：

library(ggplot2)
library(maps)
library(dplyr)
library(RColorBrewer)

nz <- map_data("nz")

value  <- data.frame(region = unique(nz$region), 
                     y = as.factor(1:length(unique(nz$region))))

nz <- nz %>%
        left_join(value, by = c("region"))

pal <- colorRampPalette(brewer.pal(22, "RdYlBu"))(22)

nzplot <- ggplot() +
  geom_polygon(aes(x = long, y = lat, group = group, fill = y), data = nz) +
  scale_fill_manual(values = pal,
                    guide = guide_legend(direction = "vertical",
                                         override.aes = list(colour = "darkgreen"), 
                                         ncol = 3))
  ggsave("nzplot.pdf", nzplot, 
       width = 89, height = 80, units = "mm")

这将创建下图：

由于 ，每个图例键都有一个深绿色边框override.aes = list(colour = "darkgreen")，但是我该如何调整这个绿色边框的粗细呢？

标签： rggplot2maps

Answer 1

边框的粗细可以通过 调整size。尝试这个：

library(ggplot2)

ggplot(mtcars, aes(mpg, fill = factor(am))) +
  geom_histogram(bins = 7) +
  guides(fill = guide_legend(override.aes = list(colour = "darkgreen", size = 5)))