r - 绘图图例中带有白色背景的符号(pt.bg 无效)

Question

我正在尝试向绘图添加图例，但无法让 pch 符号填充白色。 pt.bg 似乎没有效果:

plot(1, 1)
legend(
    x = "topright",
    legend = c("alle Messzeitpunkte", "ohne selbstinitiierte", "erwartete"),
    lty = c("solid", "dashed", "dotted"),
    pch = c(16, 1, NA),
    pt.bg = c("black", "white", NA)
)

Answer 1

pch = 1 是一个空圆圈，无法填充。 pch = 16 是一个没有边框的填充形状。 pch = 1 和 pch = 16 的颜色均由 col 定义。只有pch = 21可以填充与其边框颜色不同的颜色。 pch = 21 的填充颜色由许多绘图函数中的 bg 和 legend()< 中的 pt.bg 定义。/.

plot(1:10, rep(1, 10), ylim = c(0, 2), axes = FALSE)
legend(
    x = 1, y = 2,
    legend = c("a", "b", "c", "d", "e"),
    lty = "solid",
    pch = c(1, 1, 1),
    col = c("black", "black", "red", "red", "red"),
    pt.bg = c("black", "white", "red", "green", "blue")
)
legend(
    x = 2.5, y = 2,
    legend = c("a", "b", "c", "d", "e"),
    lty = "solid",
    pch = c(16, 16, 16),
    col = c("black", "black", "red", "red", "red"),
    pt.bg = c("black", "white", "red", "green", "blue")
)
legend(
    x = 4, y = 2,
    legend = c("a", "b", "c", "d", "e"),
    lty = "solid",
    pch = c(21, 21, 21),
    col = c("black", "black", "red", "red", "red"),
    pt.bg = c("black", "white", "red", "green", "blue")
)