渐变不同颜色的树形图上的子组ggplot2 R

这不是最漂亮的解决方案，但是将计数映射到Alpha可以模拟每种颜色的明暗梯度。aes(alpha = CNT)在内部添加geom_treemap，并根据需要缩放Alpha。

library(ggplot2)
library(treemapify)

PL <- c(rep("PL1",4),rep("PL2",4),rep("PL3",4),rep("PL4",4))
CNT <- sample(seq(1:50),16)
YEAR <- rep(c("2015","2016","2017","2018"),4)

df <- data.frame(PL,YEAR,CNT)

ggplot(df, aes(area = CNT, fill = YEAR, label=PL, subgroup=YEAR)) +

# change this line
    geom_treemap(aes(alpha = CNT)) +
    geom_treemap_subgroup_border(colour="white") +
    geom_treemap_text(fontface = "italic",
                                        colour = "white",
                                        place = "centre",
                                        grow = F,
                                        reflow=T) +
    geom_treemap_subgroup_text(place = "centre",
                                                         grow = T,
                                                         alpha = 0.5,
                                                         colour = "#FAFAFA",
                                                         min.size = 0) +
    scale_alpha_continuous(range = c(0.2, 1))

由reprex软件包（v0.2.0）创建于2018-05-03 。

编辑添加：根据这篇关于黑客攻击人造梯度的文章，通过将Alpha缩放层放置在具有较深填充的层之上。在这里，我使用了两个geom_treemaps，一个用于fill = "black"，一个用于alpha缩放。仍然有一些不足之处。

ggplot(df, aes(area = CNT, fill = YEAR, label=PL, subgroup=YEAR)) +
    geom_treemap(fill = "black") +
    geom_treemap(aes(alpha = CNT)) +
    geom_treemap_subgroup_border(colour="white") +
    geom_treemap_text(fontface = "italic",
                                        colour = "white",
                                        place = "centre",
                                        grow = F,
                                        reflow=T) +
    geom_treemap_subgroup_text(place = "centre",
                                                         grow = T,
                                                         alpha = 0.5,
                                                         colour = "#FAFAFA",
                                                         min.size = 0) +
    scale_alpha_continuous(range = c(0.4, 1))

由reprex软件包（v0.2.0）创建于2018-05-03 。