library(tidyverse)
library(ggspatial)

road = sfnetworks::roxel %>% 
  dplyr::mutate(rn = rnorm(nrow(.)))

fig_g = ggplot(data = road) +
    geom_sf(aes(color = rn),
            lwd = 0.75) +
    scale_color_gradientn(colors = c("#4575B4","#91BFDB","#E0F3F8",
                                     "#FFFFBF","#FEE090","#FC8D59"),
                          name = "random number") +
    annotation_north_arrow(location = 'tl',
                           height = unit(1, "cm"),
                           width = unit(1, "cm"),) +
    annotation_scale(location = 'bl') +
    theme_bw() +
    theme(legend.justification = c('right','bottom'),
          legend.position = "inside",
          legend.background = element_rect(fill = 'transparent'),
          legend.direction = "horizontal",
          legend.key.width = unit(15, "pt"),
          legend.key.height = unit(5, "pt"))
fig_g

注意以下几点:

  • ggplot2使用连续色带时自定义颜色使用scale_color_gradientn()函数;

  • 使用ggspatial添加指北针和比例尺时可以通过location参数指定相应在四角的位置;

  • ggplot2图例放在图主体内需指定legend.position = "inside",进而通过调整legend.justification来调整图例的具体位置;

  • 图例宽和高(图例主体,不包括图例名字)分别使用legend.key.width和legend.key.height调节

  • 图例背景透明使用legend.background = element_rect(fill = 'transparent')