如何在R中将包含符号的图形写入PDF？

# 安装和加载所需的包
install.packages("ggplot2")
install.packages("ggforce")
library(ggplot2)
library(ggforce)

# 创建一个简单的数据集
data <- data.frame(x = 1:10, y = 1:10)

# 使用ggplot2创建一个带有符号的图形
p <- ggplot(data, aes(x = x, y = y)) +
  geom_point(size = 5, color = "blue") +
  geom_text(aes(label = "A"), x = 3, y = 3, size = 7, color = "red",
            parse = TRUE, family = "Symbol")

# 将图形写入PDF文件
ggsave("output.pdf", p, device = "pdf")