# ================== 1. 安装必要包（如果尚未安装）==================
# 如果是第一次运行，请取消下面两行的注释并运行安装
# install.packages("ggplot2")
# install.packages("dplyr")
# install.packages("data.table")  # 用于 fread
# ================== 2. 加载所需库 ==================
library(ggplot2)
library(dplyr)
library(data.table)  # 使用 fread 读取表格
# ================== 3. 创建数据 ==================
df <- data.table::fread("
Feature        Gain        Cover    Frequency
UQCRC2 0.0688893642 0.0649316036 0.0415455633
MTCH2 0.0324376628 0.0273261500 0.0213711746
TBK1 0.0279487991 0.0339715594 0.0196614806
PGM1 0.0261452220 0.0329089525 0.0230808685
UTP18 0.0254163911 0.0275343985 0.0179517866
")
# 转为 data.frame（ggplot2 兼容）
df <- as.data.frame(df)
# 按 Gain 降序排序：最重要的特征在最上面
df <- df %>% arrange(desc(Gain))
# ================== 4. 绘制棒棒糖图 ==================
p <- ggplot(df, aes(x = Gain, y = reorder(Feature, Gain))) +
  # 绘制“棒”：从 x=0 到 x=Gain 的线段
  geom_segment(
    aes(x = 0, xend = Gain, yend = Feature),
    color = "gray80",
    size = 1.1
  ) +
  # 绘制“糖”：点的大小固定，颜色根据 Gain 渐变
  geom_point(aes(color = Gain), size = 4.5, shape = 16) +
  # 可选：在点右侧添加数值标签
  geom_text(
    aes(label = round(Gain, 5)),
    hjust = -0.1,
    size = 3.5,
    color = "gray20"
  ) +
  # 设置颜色渐变：浅蓝 → 深蓝
  scale_color_gradient(
    low = "yellow",   # 浅蓝色（小值）
    high = "red",   # 深红色色（大值）
    name = "Gain"
  ) +
  # 添加标题和标签
  labs(
    title = "Feature Importance by Gain",
    subtitle = "Horizontal Lollipop Chart | Sorted by Gain (Descending)",
    x = "Gain",
    y = "Feature"
  ) +
  scale_x_continuous(
    expand = expansion(mult = c(0, 0.5))  # 在 x 轴右侧添加一些空间
  ) +
  # 使用极简主题，并完全移除网格线
  theme_minimal() +
  theme(
    # 完全删除所有网格线
    panel.grid = element_blank(),
    # 坐标轴
    axis.line = element_line(color = "black", size = 0.5),
    # 文字大小
    axis.text = element_text(size = 11),
    axis.title = element_text(size = 12),
    # 标题样式
    plot.title = element_text(size = 14, face = "bold", color = "#2B2B2B"),
    plot.subtitle = element_text(size = 10, color = "gray50"),
    # 去除背景
    panel.background = element_blank(),
    # 边距
    plot.margin = margin(0.6, 1.5, 0.6, 0.6, "cm")
  )
# ================== 5. 显示图形 ==================
print(p)
# ================== 6. （可选）保存图片 ==================
# ggsave("lollipop_feature_gain.png", plot = p, width = 9, height = 4.5, dpi = 300, bg = "white")