如何在R中的不同行上绘制图例符号和标签？

legend(x, y, legend, fill, col, pch, cex, pt.cex, bg, text.col, text.font, ...)

# 创建一个空白的绘图区域
plot(0, 0, type = "n", xlim = c(0, 10), ylim = c(0, 10), xlab = "", ylab = "")

# 定义图例的位置和标签
x <- 1
y <- 9
legend_labels <- c("Group 1", "Group 2", "Group 3")

# 定义图例符号的填充颜色和边框颜色
fill_colors <- c("red", "green", "blue")
border_colors <- c("black", "black", "black")

# 定义图例符号的类型和大小
symbol_types <- c(16, 17, 18)
symbol_sizes <- c(2, 2, 2)

# 在不同行上绘制图例符号和标签
for (i in 1:length(legend_labels)) {
  legend(x, y, legend = legend_labels[i], fill = fill_colors[i], col = border_colors[i],
         pch = symbol_types[i], cex = symbol_sizes[i], pt.cex = 1.2, bg = "white",
         text.col = "black", text.font = 2)
  y <- y - 1
}