如何用R Markdown在Word中生成2×2布局的高质量ggplot2图表？

以下是三种可靠的实现方式，均能保持图表的矢量级清晰度，避免轴标题模糊的问题：

方法1：使用patchwork包（推荐，语法直观） #

patchwork是ggplot2生态中专门用于组合图表的工具，语法简洁易懂，支持灵活的布局调整。

---
title: "Test graphs"
output: word_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, dpi = 900)
library(ggplot2)
library(patchwork) # 加载组合图表的包
set.seed(1234)

wdata = data.frame(
  sex = factor(rep(c("F", "M"), each=200)),
  weight = c(rnorm(200, 55), rnorm(200, 58))
)

# 预先创建4个不同的图表
p1 <- ggplot(wdata, aes(x = weight)) + 
  geom_bar(stat = "bin", color= "black", fill="red") +
  labs(title = "直方图")

p2 <- ggplot(wdata, aes(x = sex, y = weight)) + 
  geom_boxplot(fill="blue") +
  labs(title = "箱线图")

p3 <- ggplot(wdata, aes(x = weight, fill = sex)) + 
  geom_density(alpha=0.5) +
  labs(title = "密度图")

p4 <- ggplot(wdata, aes(x = weight)) + 
  geom_histogram(aes(y=..density..), color="black", fill="green") +
  geom_density(color="red") +
  labs(title = "直方图+密度曲线")

# 用patchwork组合成2×2布局
(p1 + p2) / (p3 + p4)
# 也可以用等价写法：p1 + p2 + p3 + p4 + plot_layout(ncol=2)

## 方法2：使用gridExtra包的grid.arrange函数
这是经典的图表组合工具，适合习惯基础布局逻辑的用户：

```r
---
title: "Test graphs"
output: word_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, dpi = 900)
library(ggplot2)
library(gridExtra) # 加载gridExtra包
set.seed(1234)

wdata = data.frame(
  sex = factor(rep(c("F", "M"), each=200)),
  weight = c(rnorm(200, 55), rnorm(200, 58))
)

# 创建4个图表
p1 <- ggplot(wdata, aes(x = weight)) + 
  geom_bar(stat = "bin", color= "black", fill="red") +
  labs(title = "直方图")

p2 <- ggplot(wdata, aes(x = sex, y = weight)) + 
  geom_boxplot(fill="blue") +
  labs(title = "箱线图")

p3 <- ggplot(wdata, aes(x = weight, fill = sex)) + 
  geom_density(alpha=0.5) +
  labs(title = "密度图")

p4 <- ggplot(wdata, aes(x = weight)) + 
  geom_histogram(aes(y=..density..), color="black", fill="green") +
  geom_density(color="red") +
  labs(title = "直方图+密度曲线")

# 指定ncol=2实现2×2布局
grid.arrange(p1, p2, p3, p4, ncol=2)

## 方法3：利用knitr原生布局参数（无需额外包）
如果使用knitr 1.35及以上版本，可以直接通过代码块参数实现布局，无需加载额外包：

```r
---
title: "Test graphs"
output: word_document
---

```{r setup, include=FALSE}
knitr::opts_chunk$set(echo = FALSE, dpi = 900)
library(ggplot2)
set.seed(1234)

wdata = data.frame(
  sex = factor(rep(c("F", "M"), each=200)),
  weight = c(rnorm(200, 55), rnorm(200, 58))
)

# 依次绘制4个图表，knitr会自动排列成2×2布局
ggplot(wdata, aes(x = weight)) + 
  geom_bar(stat = "bin", color= "black", fill="red") +
  labs(title = "直方图")

ggplot(wdata, aes(x = sex, y = weight)) + 
  geom_boxplot(fill="blue") +
  labs(title = "箱线图")

ggplot(wdata, aes(x = weight, fill = sex)) + 
  geom_density(alpha=0.5) +
  labs(title = "密度图")

ggplot(wdata, aes(x = weight)) + 
  geom_histogram(aes(y=..density..), color="black", fill="green") +
  geom_density(color="red") +
  labs(title = "直方图+密度曲线")

### 注意事项
- 若未安装所需包，执行`install.packages(c("patchwork", "gridExtra"))`完成安装
- 保留`dpi=900`的设置，确保图表在Word中放大后依然清晰
- 如需调整图表间距，可在patchwork中使用`plot_spacing`参数，或在grid.arrange中使用`padding`参数

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