如何在图例上绘制线条名称而不使用颜色，线型或形状

Question

在此绘图中，我想在图例上显示红色实线的名称（“ c”）。既然那条线必须是“红色”颜色，“实心”并且没有“点形”，该怎么办？

在这种情况下，如何在图例上显示'c'行的名称？

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^{由reprex package（v0.3.0）于2019-10-30创建}

Answer 1

这是一种使用is_special列思想的方法。

df_all = rbind(df1, df2)
df_all$is_special = ifelse(df_all$line_label == "c", "y", "n")

ggplot(data = df_all, aes(x = year, y = value, color = line_label)) +
  geom_line(aes(linetype = line_label, size = is_special, alpha = is_special)) +
  geom_point(aes(shape = line_label), size = 3) +
  scale_color_manual(values=c("#BFBFBF", "#173C70", "#DA2537")) +
  scale_linetype_manual(values=c("solid", "dashed", "solid")) +
  scale_size_manual(values = c("n" = 1, "y" = 2), guide = "none") +
  scale_alpha_manual(values = c("n" = 1, "y" = 0.8), guide = "none") +
  scale_x_continuous(breaks=seq(2010, 2012, by = 1))