如何使用ggplot突出顯示更改線型或大小的線的特定區域

我有以下資料框：

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")

我繪制了每個學生在幾個月內的成績，并想知道是否有一種簡單的方法可以突出每條繪制線的特定部分，該部分對應于顯示他們成績變化最大的時間段（此資訊是已經存在于資料集中：“更改”列。在這種情況下，對于所有學生來說，這將是從 2 月到 3 月）。

嘗試使用

我如何解決它？提前致謝！n_n

uj5u.com熱心網友回復：

不要在 aes 中指定大小。使用縮放功能

關于線路設計的另一個建議見下文。

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))

另一種選擇可能是利用ggforce::geom_link在兩點之間插入美學的函式。

library(ggforce)

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

嘗試更改線型時失敗。在這種情況下，請改用 geom_segment - 不過您需要進行一些資料轉換。

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).

uj5u.com熱心網友回復：

沿其路線更改線寬是可能的（正如 tjebo 指出的那樣），但它很少能畫出漂亮的圖。更清晰的方法可能是在感興趣的區域上添加彩色背景：

library(hrbrthemes)
library(ggplot2)

ggplot(test, aes(x = Month, y = Grade, color = Student, group = Student))  
  geom_point(alpha = 0)  
  geom_rect(data = test[1,],
            aes(xmin = 'February', xmax = 'March', ymin = -Inf, ymax = Inf),
            color = NA, fill = 'deepskyblue4', alpha = 0.1)  
  geom_line(size = 1)  
  geom_point(shape = 21, fill = 'white', size = 3)  
  theme_minimal()  
  scale_color_manual(values = c('pink3', 'orange2', 'red4'))  
  theme_tinyhand()

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