ggplot折线图保留指定颜色线型并添加对应图例

ggplot2 仅会对aes()内部映射的视觉属性自动生成图例。你现有代码把三条线的颜色、线型参数都写在aes()外部作为固定值传入，系统无法将这些视觉属性和分组标签关联，因此不会渲染图例。

完全保留你预设的所有线条颜色、线型、线宽参数，仅调整映射逻辑补全图例，修正后代码如下：

RecoveryCombined <- as.data.frame(RecoveryCombined)
plotcombined <- ggplot(data = RecoveryCombined, aes(x = t)) + 
  geom_line(aes(y = BP0, color = "BP0", linetype = "BP0"), lwd = 0.9) + 
  geom_line(aes(y = BP30, color = "BP30", linetype = "BP30"), lwd = 0.9) +
  geom_line(aes(y = BP60, color = "BP60", linetype = "BP60"), lwd = 0.9) +
  facet_wrap(~k + g) +  
  scale_x_continuous(breaks = seq(0, 10, by = 1)) +
  # 匹配原有颜色参数，无样式改动
  scale_color_manual(values = c(
    "BP0" = "cornflowerblue",
    "BP30" = "chocolate1",
    "BP60" = "darkslategrey"
  )) +
  # 匹配原有线型参数，无样式改动
  scale_linetype_manual(values = c(
    "BP0" = "solid",
    "BP30" = "twodash",
    "BP60" = "longdash"
  )) +
  labs(
    title = "Recovery Trajectory for BI = 200", 
    x = "Time Period", 
    y = "Relative Performance", 
    color = "Legend",
    linetype = "Legend"
  )
print(plotcombined)

• 所有线条视觉效果和你原代码输出完全一致，不会破坏现有配图风格
• 颜色、线型映射共用同一个图例，不会出现重复的双图例问题
• 无需转换数据格式，代码改动量最小
• 已移除原代码中labs()末尾多余的+语法错误

内容的提问来源于stack exchange，提问作者Emma Kuttler