如何用R的ggplot绘制目标组合图？双折线无法正常显示求解

首先需要对数据进行预处理，将带百分比符号的字符转换为数值，同时在折线图中按member_casual分组，才能画出两条折线。以下是完整可运行的代码：

# 加载必要包
library(ggplot2)
library(dplyr)

# 你的数据集
yearly_percentage <- structure(list(year = c("2016", "2016", "2017", "2017", "2018", 
"2018", "2019", "2019", "2020", "2020"), member_casual = c("casual", 
"member", "casual", "member", "casual", "member", "casual", "member", 
"casual", "member"), count_percentage = c("23.88%", "76.12%", 
"21.86%", "78.14%", "18.79%", "81.21%", "23.06%", "76.94%", "11.31%", 
"88.69%"), ride_Length = c("45%", "55%", "42%", "58%", "46.6%", 
"53.4%", "51.5%", "48.5%", "42%", "58%")), class = c("tbl_df", 
"tbl", "data.frame"), row.names = c(NA, -10L))

# 数据预处理：去除%并转为数值
yearly_percentage <- yearly_percentage %>%
  mutate(
    count_percentage = as.numeric(sub("%", "", count_percentage)),
    ride_Length = as.numeric(sub("%", "", ride_Length)),
    year = factor(year) # 将年份转为因子，保证x轴顺序正确
  )

# 绘制组合图
ggplot(yearly_percentage, aes(x = year)) +
  # 分组柱状图
  geom_bar(aes(y = count_percentage, fill = member_casual), 
           position = "dodge", stat = "identity", alpha = 0.7) +
  # 两条折线：按member_casual分组，设置颜色区分
  geom_line(aes(y = ride_Length, color = member_casual, group = member_casual), 
            linewidth = 1.2) +
  # 添加折线的点标记
  geom_point(aes(y = ride_Length, color = member_casual), size = 3) +
  # 设置坐标轴标签和标题
  labs(
    x = "年份",
    y = "百分比",
    fill = "用户类型",
    color = "用户类型",
    title = "年度用户占比与骑行时长占比组合图"
  ) +
  # 调整主题样式
  theme_minimal() +
  theme(plot.title = element_text(hjust = 0.5))

问题分析 #

1. 数据类型错误：原数据中的count_percentage和ride_Length是带%的字符型，ggplot无法正确识别为数值进行绘图，必须转换为数值型。
2. 折线图未分组：原代码的geom_line没有指定group = member_casual，ggplot无法区分不同用户类型的数据点，因此只能画出一条混乱的线，而不是两条分别对应casual和member的折线。
3. 年份轴顺序：将年份转为因子可以保证x轴按时间顺序排列，避免字符型年份排序混乱。

内容的提问来源于stack exchange，提问作者El Joven