自定义ggplot图例

jlo 发表于 Dev

JLO

假设我有一些数据，并且想使用ggplot绘制预测和95％的预测间隔。以下代码有效，并给出了可接受的图例。

ExampleData = data.frame(t = 1:10, f = rep(1,10), Lower = rep(0.5, 10), Upper = rep(1.5, 10))
library (ggplot2)
ggplot(data = ExampleData)+
  geom_point(aes(x=t, y =f, colour = "Forecasts"))+
  geom_point(aes(x=t, y =Lower), shape=95)+
  geom_segment(aes(x=t, y = Lower, xend=t, yend = f))+
  geom_point(aes(x=t, y =Upper), shape=95)+
  geom_segment(aes(x=t, y = f, xend=t, yend = Upper))+
  geom_vline(aes(xintercept = 11, colour = "95% PI"))+
  scale_colour_manual(values = c("95% PI" = "black","Forecasts" = "red"),
                      guide = guide_legend(override.aes = list(
                        linetype = c('solid','blank'),
                        shape = c(NA,16))))+
  scale_x_continuous(name="Time", limits=c(1, 10), breaks = c(0,5,10))+
  labs(title="Example")+
  labs(y = "Forecasts")+
  theme_bw()

我也想添加一条水平线，例如y = 0.75。但是，图例似乎无法容纳水平和垂直线。有没有一种方法可以使用ggplot做到这一点？还包括较短的水平线呢？例如，上下点由短水平线表示。

阿德拉

我更新了@Slagt答案，以将点添加到图例中：

library (ggplot2)
ExampleData = data.frame(t = 1:10, f = 1, Lower = 0.5, Upper = 1.5)

ggplot(data = ExampleData, aes(x = t)) + 
  geom_errorbar(aes(ymin = Lower, ymax = Upper, color = "95% PI"), width = 0) + 
  geom_point(aes(y = f, color = "Forecasts")) + 
  geom_line(aes(y = 0.75, color = "Threshold")) + 
  scale_colour_manual(values = c("95% PI"    = "black",
                                 "Forecasts"  = "red",
                                 "Threshold" = "green"),
                      guide = guide_legend(override.aes = list(
                        linetype = c("blank", "blank", "solid"),
                        shape    = c(124, 16, NA),
                        size     = c(5, 1.5, 0.5)))) + 
  theme_bw() + 
  scale_x_continuous(name="Time", breaks = c(0, 5, 10)) + 
  labs(title = "Example", y = "Forecasts")

垂直线的特殊形状非常不错。但是，也应该可以在图例中旋转线。可以通过以下修改GeomErrorbar$draw_key和GeomLine$draw_key功能来完成：

library(grid)
GeomErrorbar$draw_key <- function(data, params, size) 
{
  segmentsGrob(x0 = 0.5, y0 = 0, x1 = 0.5, y1 = 1, 
               gp = gpar(col = alpha(data$colour, data$alpha), 
                         lwd = data$size * .pt, 
                         lty = ifelse(data$colour == "green", 
                                      0, data$linetype), 
                         lineend = "butt"))
}
GeomLine$draw_key <- function(data, params, size) 
{
  segmentsGrob(x0 = 0, y0 = 0.5, x1 = 1, y1 = .5, 
               gp = gpar(col = alpha(data$colour, data$alpha), 
                         lwd = data$size * .pt, 
                         lty = ifelse(data$colour == "black", 
                                      0, data$linetype), 
                         lineend = "butt"))
}

因为geom_errorbar我将图例线设置为垂直，而geom_line将其设置为水平。为了防止交叉效果，我为lty基于颜色的参数添加了条件。

然后只需创建图：

ggplot(data = ExampleData, aes(x = t)) + 
  geom_errorbar(aes(ymin = Lower, ymax = Upper, color = "95% PI"), 
                width = 0) + 
  geom_point(aes(y = f, color = "Forecasts")) + 
  geom_line(aes(y = 0.75, color = "Threshold")) + 
  scale_colour_manual(values = c("95% PI"    = "black",
                                 "Forecasts"  = "red",
                                 "Threshold" = "green"),
                      guide = guide_legend(override.aes = list(
                        linetype = c("solid", "blank", "solid"),
                        shape = c(NA, 16, NA)))) + 
  theme_bw() + 
  scale_x_continuous(name="Time", breaks = c(0, 5, 10)) + 
  labs(title = "Example") + labs(y = "Forecasts")