r - 如何使用 ggplot 突出显示更改线型或大小的线的特定区域

Question

我有以下数据框:

test = structure(list(Student = c("Ana", "Brenda", "Max", "Ana", "Brenda", 
"Max", "Ana", "Brenda", "Max"), Month = structure(c(1L, 1L, 1L, 
2L, 2L, 2L, 3L, 3L, 3L), .Label = c("January", "February", "March"
), class = "factor"), Grade = c(7L, 6L, 7L, 8L, 6L, 7L, 5L, 10L, 
10L), Change = c("February", "February", "February", "February", 
"February", "February", "February", "February", "February")), row.names = c(NA, 
-9L), class = "data.frame")

我绘制了每个学生几个月的成绩，并想知道是否有一种简单的方法来强调每条绘制线的特定部分，该部分对应于成绩变化最大的时间段(此信息已存在于数据集中:“更改”列。在本例中，对于所有学生来说，时间范围为二月到三月。

尝试使用类似的逻辑 here, to change the color a specific part of the line我尝试更改线条的线型和/或大小(因为我已经使用颜色来分组和显示每个学生)，以突出显示线条的特定部分。然而，事情似乎并不那么简单。

我的尝试如下:

ggplot(test, aes(x = Month, y = Grade, color = Student, group = Student)) + 
+     geom_point() + geom_line(data = test, aes(linetype = (ifelse(Month == Change, "solid", "dashed")))) 

这产生了错误:

Error: geom_path: If you are using dotted or dashed lines, colour, size and linetype must be constant over the line

还有

ggplot(test, aes(x = Month, y = Grade, color = Student, group = Student)) + 
    geom_point() + geom_line(data = test, aes(size = (ifelse(Month == Change, 1, 0.8)))) 

这有点像我正在寻找的，但看起来很糟糕，而且看起来并不像它使用我试图指定的行的大小:

如何修复它？提前致谢! n_n

Answer 1

不要指定 aes 格式的大小。使用缩放功能

有关生产线设计的其他建议，请参见下文。

test = structure(list(Student = c("Ana", "Brenda", "Max", "Ana", "Brenda", 
                                  "Max", "Ana", "Brenda", "Max"), Month = structure(c(1L, 1L, 1L, 
                                                                                      2L, 2L, 2L, 3L, 3L, 3L), .Label = c("January", "February", "March"
                                                                                      ), class = "factor"), Grade = c(7L, 6L, 7L, 8L, 6L, 7L, 5L, 10L, 
                                                                                                                      10L), Change = c("Februrary", "Februrary", "Februrary", "Februrary", 
                                                                                                                                       "Februrary", "Februrary", "Februrary", "Februrary", "Februrary"
                                                                                                                      )), row.names = c(NA, -9L), class = "data.frame")
## typo corrected
test$Change <- "February"

library(ggplot2)

ggplot(test, aes(x = Month, y = Grade, color = Student, group = Student)) + 
  geom_point() +
  ## don't specify size in aes
  geom_line(data = test, aes(size = Month == Change)) +
  ## change the size scale
  scale_size_manual(values = c(`TRUE` = 2, `FALSE` = .8))

另一种选择可能是使用ggforce::geom_link函数，它可以在两点之间插入美学。

library(ggforce)

ggplot(test, aes(x = Month, y = Grade, color = Student, group = Student)) + 
  geom_point() +
  geom_link2(data = test, aes(size = Grade, ), lineend = "round") 

尝试更改线路类型时失败。在这种情况下，请使用 geom_segment - 不过您将需要一些数据转换。

library(tidyverse)

test %>%
  group_by(Student) %>%
  mutate(xend = lead(Month), yend = lead(Grade)) %>%
ggplot(aes(x = Month, y = Grade, color = Student, group = Student)) + 
  geom_point() +
  geom_segment(aes(xend = xend, yend = yend, linetype = Month == Change)) +
  # need to specify your x
  scale_x_discrete(limits = unique(test$Month))
#> Warning: Removed 3 rows containing missing values (geom_segment).