去除图例符号的边框

Question

我正在尝试绘制一些预测与实际数据的图表，类似于以下内容：

# Some random data
x <- seq(1: 10)
y_pred <- runif(10, min = -10, max = 10)
y_obs <- y_pred + rnorm(10)
# Faking a CI
Lo.95 <- y_pred - 1.96
Hi.95 <- y_pred + 1.96
my_df <- data.frame(x, y_pred, y_obs, Lo.95, Hi.95)

ggplot(my_df, aes(x = x, y = y_pred)) +
  geom_line(aes(colour = "Forecasted Data"), size = 1.2) +
  geom_point(aes(x = x, y = y_obs, colour = "Actual Data"), size = 3) +
  geom_ribbon(aes(ymin=Lo.95, ymax=Hi.95, x=x, linetype = NA,  colour = "Confidence Interval"), alpha=0.2) +
  theme_grey() +
  scale_colour_manual(
    values = c("gray30", "blue", "red"),
    guide = guide_legend(override.aes = list(
      border=c(NA, NA, NA), 
      fill=c("gray30", "white", "white"),
      linetype = c("blank", "blank", "solid"),
      shape = c(NA, 19, NA)))) 

这个图像看起来是这样的:

我的唯一问题是图例中线条（即预测数据）的符号周围有红色边框。有没有办法在不破坏图像的其他部分的情况下将其去除呢？

- Kev W.

---

我建议这里的根本问题是您将数据映射到颜色的方式。例如aes(color = "Actual Data")并不是正确的用法。通常，我们使用aes()来映射变量（列名未引用）。我会收集数据以创建一个指示是否观察到或预测y的列，然后使用带有aes()的geom_point()将点按该列着色。 - neilfws

Answer 1

我认为 geom_ribbon 是问题所在。如果我们在 aes 中去掉它的 color 和 fill，一切看起来都很好。

library(ggplot2)

# Some random data
x <- seq(1: 10)
y_pred <- runif(10, min = -10, max = 10)
y_obs <- y_pred + rnorm(10)
# Faking a CI
Lo.95 <- y_pred - 1.96
Hi.95 <- y_pred + 1.96
my_df <- data.frame(x, y_pred, y_obs, Lo.95, Hi.95)

m1 <- ggplot(my_df, aes(x = x, y = y_pred)) +
  geom_point(aes(x = x, y = y_obs, colour = "Actual"), size = 3) +
  geom_line(aes(colour = "Forecasted"), size = 1.2) +
  geom_ribbon(aes(x = x, ymin = Lo.95, ymax = Hi.95), 
              fill = "grey30", alpha = 0.2) +
  scale_color_manual("Legend", 
                     values = c("blue", "red"),
                     labels = c("Actual", "Forecasted")) +
  guides( color = guide_legend(
    order = 1,
    override.aes = list(
                        color = c("blue", "red"),
                        fill  = c("white", "white"),
                        linetype = c("blank", "solid"),
                        shape = c(19, NA)))) +
  theme_bw() +
  # remove legend key border color & background
  theme(legend.key = element_rect(colour = NA, fill = NA),
    legend.box.background = element_blank())
m1

当我们在aes中省略置信区间(Confidence Interval)时，将不再显示其图例。一种解决方法是创建一个隐形的点，并使用一个未使用过的geom手动创建图例键。在这里，我们可以使用大小/形状 (size/shape)（感谢这个答案）。

m2 <- m1 +
  geom_point(aes(x = x, y = y_obs, size = "Confidence Interval", shape = NA)) +
  guides(size = guide_legend(NULL, 
                             order = 2,
                             override.aes = list(shape = 15, 
                                                 color = "lightgrey",
                                                 size = 6))) +
  # Move legends closer to each other
  theme(legend.title = element_blank(),
        legend.justification = "center",
        legend.spacing.y = unit(0.05, "cm"),
        legend.margin = margin(0, 0, 0, 0),
        legend.box.margin = margin(0, 0, 0, 0)) 
m2

2018年3月19日由 reprex包 (v0.2.0) 创建。

- Tung

Answer 2

更好的解决这个问题的方法是在geom_ribbon()中指定show.legend = F选项。这将消除添加和合并置信区间图例键的第二步骤的需要。以下是稍作修改的代码。

  ggplot(my_dff, aes(x = x, y = y_pred)) +
    geom_line(aes(colour = "Forecasted Data"), size = 1) +
    geom_point(aes(x = x, y = y_obs, colour = "Actual Data"), size = 1) +
    geom_ribbon(aes(ymin=Lo.95, ymax=Hi.95, x=x, linetype = NA,  colour = "Confidence Interval"), alpha=0.2, show.legend = F) +
    theme_grey() +
    scale_colour_manual(
      values = c("blue", "gray30", "red"))+
      guides(color = guide_legend(
        override.aes = list(linetype = c(1, 1, 0)), 
        shape = c(1, NA, NA),
        reverse = T))

我的情节

感谢https://stackoverflow.com/users/4282026/marblo 对类似问题的回答。

- Kay Jay