如何让R ggplot折线图跳过缺失数据点，解决手动色阶值不足报错

问题原因 #

1. 报错"Error: Insufficient values in manual scale. 4 needed but only 3 provided."是因为scale_color_manual中仅配置了3种颜色，而你的athlete字段共有4个不同取值（包含缺席的受试者），颜色数量和分组数量不匹配。
2. 要保留缺席受试者的折线，需要先补全数据集内所有受试者和所有测试周的组合，缺失的测试数据填充为NA即可，ggplot会自动跳过NA值但保留对应分组的折线。

操作步骤 #

1. 先补全数据集：

library(tidyr)

# 生成所有受试者和测试周的全组合，缺失的峰值速度填充为NA
Jump_tibble_completed <- Jump_tibble %>%
  complete(athlete, game)

2. 修改绘图代码，补全第四种颜色、替换为补全后的数据集：

Jump_vel_tracking <- ggplot(Jump_tibble_completed, aes(x = game, y = daily_max_vel, color = athlete)) + 
# 新增第四种颜色对应第四名受试者，可根据需求调整颜色值
scale_color_manual(values = c("red" , "blue", "purple", "green")) +
geom_point(na.rm = TRUE) + 
geom_line(aes(group = athlete), na.rm = TRUE) + 
scale_y_continuous(breaks = seq(from = 3.0, to = 3.8, by = 0.1), limits = c(3.0, 3.8)) + 
labs(x = 'Game', y = 'Peak Velocity (m/s)', title = "Season CMJ Peak Velocity") +
theme(panel.background = element_rect (fill = 'gray88', colour = 'orange')) + 
theme(plot.background = element_rect (fill = 'orange', color = 'orange')) +
theme(panel.grid = element_blank()) +
theme(legend.position = 'none',
      legend.title = element_blank(),
      legend.background = element_rect(fill = 'orange'),
      legend.key = element_rect(fill = 'orange')) +
theme(axis.text.x = element_text(size = 10, angle = 0)) +
theme(axis.title.x=element_blank())

Jump_vel_tracking

内容的提问来源于stack exchange，提问作者Ben McCarthy