问题原因 #

非Windows系统中，直接指定family = "Arial"会触发PostScript字体数据库找不到该字体的警告——因为系统里实际安装的是Arial的替代字体Liberation Sans，R的grid渲染系统无法自动关联两者，且常规的theme设置无法直接让geom_text继承字体配置。

有效解决方案 #

方案1：用showtext包映射并加载字体

showtext可以绕过系统字体数据库限制，直接加载TTF字体并映射为"Arial"名称，让ggplot2的所有文本元素统一使用该字体：

library(ggplot2)
library(showtext)

# 初始化showtext，让ggplot2使用其文本渲染引擎
showtext_auto()

# 将Liberation Sans字体映射为"Arial"（需确保字体文件路径正确，可通过`fc-list | grep LiberationSans`查看）
font_add("Arial", "LiberationSans-Regular.ttf")

# 生成示例数据
set.seed(123)
data <- data.frame(
  x = rnorm(20, mean = 50, sd = 10),
  y = rnorm(20, mean = 50, sd = 10),
  label = paste("P", 1:20, sep = "")
)

# 绘图，无需在geom_text中重复指定family
ggplot(data, aes(x = x, y = y)) +
  geom_point(color = "blue", size = 3) +
  geom_text(aes(label = label), vjust = -1, hjust = 0.5, size = 5, color = "red") +
  theme_minimal(base_family = "Arial") +
  labs(title = "Random Scatter Plot with Labels",
       x = "X-axis",
       y = "Y-axis")

方案2：直接使用Liberation Sans的原生字体名称

跳过映射步骤，直接指定系统识别的Liberation Sans字体名称，避免字体名称不匹配问题：

library(ggplot2)

# 生成示例数据
set.seed(123)
data <- data.frame(
  x = rnorm(20, mean = 50, sd = 10),
  y = rnorm(20, mean = 50, sd = 10),
  label = paste("P", 1:20, sep = "")
)

# 绘图时直接指定真实字体名称
ggplot(data, aes(x = x, y = y)) +
  geom_point(color = "blue", size = 3) +
  geom_text(aes(label = label), vjust = -1, hjust = 0.5, size = 5, color = "red", family = "Liberation Sans") +
  theme_minimal() +
  theme(text = element_text(family = "Liberation Sans")) +
  labs(title = "Random Scatter Plot with Labels",
       x = "X-axis",
       y = "Y-axis")

方案3：用extrafont导入字体到R数据库（适合PDF输出）

如果需要输出带嵌入字体的PDF，可通过extrafont将Liberation Sans导入R的PostScript字体数据库：

# 首次使用需安装并导入字体
install.packages("extrafont")
library(extrafont)
font_import(pattern = "LiberationSans")  # 仅导入Liberation Sans系列字体
loadfonts()  # 加载字体数据库

# 绘图
library(ggplot2)
set.seed(123)
data <- data.frame(
  x = rnorm(20, mean = 50, sd = 10),
  y = rnorm(20, mean = 50, sd = 10),
  label = paste("P", 1:20, sep = "")
)

ggplot(data, aes(x = x, y = y)) +
  geom_point(color = "blue", size = 3) +
  geom_text(aes(label = label), vjust = -1, hjust = 0.5, size = 5, color = "red", family = "Liberation Sans") +
  theme_minimal(base_family = "Liberation Sans") +
  labs(title = "Random Scatter Plot with Labels",
       x = "X-axis",
       y = "Y-axis")

# 保存PDF时嵌入字体
ggsave("scatter_plot.pdf", device = cairo_pdf)

注意事项 #

• 可通过fc-list | grep "Liberation Sans"命令在Linux系统中查看字体的准确名称和文件路径
• 若使用RStudio，修改字体配置后建议重启R会话确保生效
• 如果font_add找不到字体文件，可指定完整路径，例如font_add("Arial", "/usr/share/fonts/truetype/liberation/LiberationSans-Regular.ttf")

内容的提问来源于stack exchange，提问作者Caterina