如何在R中手动生成包含颜色、形状和线型的统一图例？

你的代码当前生成了两个独立图例，要合并成包含所有指定元素的统一图例，核心是让所有美学映射共享同一套标签体系，再通过override.aes精准控制每个图例项的显示样式，同时关闭多余的图例引导。

修改后的完整代码 #

ggplot() +
  # 底图元素（无需图例，不加入aes映射）
  geom_sf(data = all_boundaries$osm_multipolygons,
          color = "lightgrey", size = 0.7, alpha = 0.8) + 
  geom_sf(data = all_boundaries$osm_lines,
          linetype = "dotted", color = "#D55E00", size = 0.7, alpha = 0.8) +
  geom_sf(data = coast$osm_lines,
          color = "#56B4E9", size = 12) +
  coord_sf(xlim = c(-113.517109, -117.823506), 
           ylim = c(30.742140, 33.961826), expand = FALSE) +
  theme_bw() + 
  labs(x = NULL, y = NULL) +
  
  # 需展示图例的元素：用统一标签关联美学属性
  geom_path(data = ros, aes(x = long, y = lat, linetype = "Mexican ducts", color = "Mexican ducts"), alpha = 0.5) +
  geom_point(aes(x = -116.8476211, y = 31.9885162, color = "LNG terminal", shape = "LNG terminal"), fill = "#CC79A7", size = 2) +
  geom_line(data = amp, aes(x = long, y = lat), alpha = 0.5) + # 该元素无需图例，不设置标签
  geom_path(data = nbaja, aes(x = lat, y = long, linetype = "US ducts", color = "US ducts"), alpha = 0.5) +
  geom_path(data = sand, aes(x = long, y = lat), linetype = "longdash", alpha = 0.5) + # 无需图例
  geom_path(data = soca, aes(x = long, y = lat), linetype = "longdash", alpha = 0.5) + # 无需图例
  geom_point(aes(x = -115.428521, y = 32.669708, shape = "Interconnectors", color = "Interconnectors"), fill = "#000000") +
  geom_point(aes(x = -116.898, y = 32.5534, shape = "Interconnectors", color = "Interconnectors"), fill = "#000000") +
  geom_point(aes(x = -114.773898, y = 32.715056, shape = "Interconnectors", color = "Interconnectors"), fill = "#000000") +
  geom_point(data = plants, aes(x = long, y = lat, color = "Power plants", shape = "Power plants"), fill = "#D55E00", alpha = 0.5, size = 1.5) +
  
  # 颜色比例尺：统一所有标签的颜色值
  scale_color_manual(
    values = c(
      "Power plants" = "#D55E00", 
      "LNG terminal" = "#CC79A7", 
      "Interconnectors" = "#000000", 
      "Mexican ducts" = "#999999", 
      "US ducts" = "#999999"
    ),
    labels = c("Power plants", "LNG terminal", "Interconnectors", "Mexican ducts", "US ducts")
  ) +
  
  # 形状比例尺：给无需形状的项设为NA
  scale_shape_manual(
    values = c(
      "Power plants" = 21, 
      "LNG terminal" = 15, 
      "Interconnectors" = 23, 
      "Mexican ducts" = NA, 
      "US ducts" = NA
    ),
    labels = c("Power plants", "LNG terminal", "Interconnectors", "Mexican ducts", "US ducts")
  ) +
  
  # 线型比例尺：给无需线型的项设为NA
  scale_linetype_manual(
    values = c(
      "Power plants" = NA, 
      "LNG terminal" = NA, 
      "Interconnectors" = NA, 
      "Mexican ducts" = "solid", 
      "US ducts" = "longdash"
    ),
    labels = c("Power plants", "LNG terminal", "Interconnectors", "Mexican ducts", "US ducts")
  ) +
  
  # 合并图例：仅保留一个引导，统一设置样式
  guides(
    color = guide_legend(
      title = "Legend",
      override.aes = list(
        shape = c(21, 15, 23, NA, NA),
        linetype = c(NA, NA, NA, "solid", "longdash")
      )
    ),
    shape = "none",  # 关闭单独的形状图例
    linetype = "none" # 关闭单独的线型图例
  )

关键修改说明 #

• 统一标签体系：所有需入图例的元素，用相同标签关联color/shape/linetype，让ggplot识别它们属于同一组图例项。
• 补充线型比例尺：新增scale_linetype_manual，给点类元素的线型设为NA，避免干扰显示。
• 合并图例引导：仅保留color的图例引导，通过override.aes为每个图例项指定对应形状、线型，同时关闭shape和linetype的单独图例。
• 清理冗余设置：移除底图元素的inherit.aes = TRUE（无需继承映射），以及原scale中多余的guide参数，避免冲突。

内容的提问来源于stack exchange，提问作者Lilia