我有一个 ggplot,我将因子映射到填充和 alpha,如下所示:
set.seed(47)
the_data <- data.frame(value = rpois(6, lambda=20),
cat1 = rep(c("A", "B"), each = 3),
cat2 = rep(c("X", "Y", "Z"), 2))
ggplot(the_data, aes(y = value, x = cat2, alpha = cat1, fill = cat2)) +
geom_bar(stat = "identity", position = "dodge") +
scale_alpha_discrete(range = c(0.5, 1)) +
theme_bw()
我为其制作它的人并没有发现 alpha 的图例非常清楚。我认为一个很好的替代方案是这样的(我在基本图形中将其组合在一起):
我知道我无法使用高级 ggplot 命令生成这样的图例,但是我可以在 grid
中生成图例并将其放在我的绘图之上吗?
最佳答案
这是一个可能的起点。我创建了两个不同的图,它们具有适当的图例 - 一个“明亮”和一个“苍白”。从绘图对象中提取图例。然后使用网格视口(viewport)(一个用于绘图,一个用于每个图例)将各个部分组合在一起。
library(grid)
library(gtable)
# create plot with legend with alpha = 1
g1 <- ggplot(the_data, aes(y = value, x = cat2, alpha = cat1, fill = cat2)) +
geom_bar(stat = "identity", position = "dodge") +
scale_alpha_discrete(range = c(0.5, 1)) +
theme_bw() +
guides(fill = guide_legend(title = "A",
title.hjust = 0.4),
alpha = FALSE) +
theme_bw() +
theme(legend.text = element_blank())
g1
# grab legend
legend_g1 <- gtable_filter(ggplot_gtable(ggplot_build(g1)), "guide-box")
# create plot with 'pale' legend
g2 <- ggplot(the_data, aes(y = value, x = cat2, alpha = cat1, fill = cat2)) +
geom_bar(stat = "identity", position = "dodge") +
scale_alpha_discrete(range = c(0.5, 1)) +
guides(fill = guide_legend(override.aes = list(alpha = 0.5),
title = "B",
title.hjust = 0.3),
alpha = FALSE) +
theme_bw()
g2
# grab legend
legend_g2 <- gtable_filter(ggplot_gtable(ggplot_build(g2)), "guide-box")
# arrange plot and legends
# legends to the right
# define plotting regions (viewports)
vp_plot <- viewport(x = 0.4, y = 0.5,
width = 0.8, height = 1)
vp_legend_g1 <- viewport(x = 0.85, y = 0.5,
width = 0.4, height = 0.4)
vp_legend_g2 <- viewport(x = 0.90, y = 0.5,
width = 0.4, height = 0.4)
# clear current device
grid.newpage()
# add objects to the viewports
# plot without legend
print(g1 + theme(legend.position = "none"), vp = vp_plot)
upViewport(0)
pushViewport(vp_legend_g1)
grid.draw(legend_g1)
upViewport(0)
pushViewport(vp_legend_g2)
grid.draw(legend_g2)
# legends on top
vp_plot <- viewport(x = 0.5, y = 0.4,
width = 1, height = 0.85)
vp_legend_g1 <- viewport(x = 0.5, y = 0.9,
width = 0.4, height = 0.4)
vp_legend_g2 <- viewport(x = 0.55, y = 0.9,
width = 0.4, height = 0.4)
grid.newpage()
print(g1 + theme(legend.position = "none"), vp = vp_plot)
upViewport(0)
pushViewport(vp_legend_g1)
grid.draw(legend_g1)
upViewport(0)
pushViewport(vp_legend_g2)
grid.draw(legend_g2)
关于r - 在网格中制作一个矩形图例,并标记行和列,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/20129299/