使用 ggplot2 打造可视化

R
Visualization
快速回顾 ggplot2 的语法结构，并通过示例演示图形语法的组合。
Author

Siyu Wu

Published

September 30, 2025

ggplot2 让数据可视化像搭积木一样高效优雅。

核心理念

ggplot2 的设计基于 Grammar of Graphics。我们通过图层（layer）叠加的方式构建图形，流程通常包含：

  1. 准备数据框（data）。
  2. 映射变量到美学属性（aes）。
  3. 选择几何对象（geom_*）。
  4. 根据需要添加统计转换、坐标系统和主题。

快速示例

library(ggplot2)
Warning: package 'ggplot2' was built under R version 4.4.3
ggplot(mpg, aes(x = displ, y = hwy, color = class)) +
  geom_point(size = 2.5, alpha = 0.8) +
  geom_smooth(method = "loess", se = FALSE) +
  labs(
    title = "发动机排量与高速油耗",
    x = "排量 (L)",
    y = "高速油耗 (mpg)",
    color = "车型"
  ) +
  theme_minimal(base_size = 12)
`geom_smooth()` using formula = 'y ~ x'
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: span too small.  fewer data values than degrees of freedom.
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: pseudoinverse used at 5.6935
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: neighborhood radius 0.5065
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: reciprocal condition number 0
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: There are other near singularities as well. 0.65044
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: pseudoinverse used at 4.008
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: neighborhood radius 0.708
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: reciprocal condition number 0
Warning in simpleLoess(y, x, w, span, degree = degree, parametric = parametric,
: There are other near singularities as well. 0.25

延伸阅读

  • facet_* 系列函数用于分面。
  • scale_* 控制颜色、形状与坐标轴。
  • theme() 修改图形细节。

搭配 dplyr 管道与自定义主题，可以快速构建产品级别的图表模板。