ggplot2：移动（重新定位）图例以免阻塞图形框

Posted 2023-02-16

【中文标题】ggplot2：移动（重新定位）图例以免阻塞图形框

【英文标题】：ggplot2: move (reposition) the legend so as not to block the graph box

【发布时间】：2020-09-12 02:45:44

【问题描述】：

如何将图例向左和底部移动几个点（图形框线的宽度）？

任务：我想让图例的背景半透明，但不与图形框重叠。

（红色边框 - 更好地显示问题）

使用代码：

image + theme(
    panel.background     = element_rect(fill = "white", color = NA),
    panel.border         = element_rect(fill = NA, color = "black", size = 2),
    panel.grid.major     = element_line(color = "#00000040", linetype = 3),

    axis.text            = element_text(size = 10),
    axis.title           = element_text(size = 12),
    axis.title.x         = element_text(margin = margin(t = 10)),
    axis.title.y         = element_text(margin = margin(r = 10)),

    legend.key           = element_rect(fill = NA, color = NA),
    legend.background    = element_rect(fill = "#ffffff80", color = "red", size = 1),
    legend.justification = c(1, 1),
    legend.position      = c(1, 1),
    legend.title         = element_text(size = 10, color = "black"),

    plot.title           = element_text(hjust = 0.5),
)

【参考方案1】：

如果您希望图例框与绘图边框的外边缘对齐，您需要调整legend.box.margin，使顶部边缘与legend.background 中定义的线的宽度具有相同的值。

没有样本数据，所以我创建了一些：

library(ggplot2)

x  <- seq(0, 2 * pi, length.out = 100)
df <- data.frame(x = c(x, x), y = c(-cos(x), sin(x)), 
                 group = rep(c("data1", "data2"), each = 100))

image <- ggplot(df, aes(x, y)) + 
  geom_line(aes(colour = group)) + 
  scale_colour_manual(values = c("red", "black"))

image + theme(
    panel.background     = element_rect(fill = "white", color = NA),
    panel.border         = element_rect(fill = NA, color = "black", size = 2),
    panel.grid.major     = element_line(color = "#00000040", linetype = 3),

    axis.text            = element_text(size = 10),
    axis.title           = element_text(size = 12),
    axis.title.x         = element_text(margin = margin(t = 10)),
    axis.title.y         = element_text(margin = margin(r = 10)),

    legend.key           = element_rect(fill = NA, color = NA),
    legend.background    = element_rect(fill = "#ffffff80", color = "red", size = 1),
    legend.justification = c(1, 1),
    legend.position      = c(1, 1),
    legend.title         = element_text(size = 10, color = "black"),
    legend.box.margin    = margin(1, 0, 0, 0),

    plot.title           = element_text(hjust = 0.5)
)

^{由reprex package (v0.3.0) 于 2020 年 5 月 25 日创建}

【参考方案2】：

找到了！

legend.box.margin    = margin(t = 2, r = 2),