如何为表格中的每一列创建热图 [英] How to create a heat Map for each column in a table

问题描述

我想创建一个热图，显示整个列中颜色的最大值(浅蓝色)和最低值(深蓝色)以及不同的阴影.这应该在逐列的基础上，而不是在整个表中.

I would like to create a heat map showing the highest value in a colour maybe light blue and the lowest value in dark blue and different shades throughout the column. This should be on a column by column basis not on the full table.

我该怎么做?

示例代码:

library(gtable)
library(grid)
library(gridExtra)

g <- tableGrob(iris[1:4, 1:3])
g <- gtable_add_grob(g,
    grobs = rectGrob(gp = gpar(fill = NA, lwd = 2)),
    t = 2, b = nrow(g), l = 1, r = ncol(g))
g <- gtable_add_grob(g,
    grobs = rectGrob(gp = gpar(fill = NA, lwd = 2)),
    t = 1, l = 1, r = ncol(g))
grid.draw(g)

推荐答案

您可以通过定义主题来实现

You can do it by defining a theme

library(gtable)
library(grid)
library(gridExtra)

iris <- as.matrix(iris[1:4, 1:3])

# a simple function to scale each column to the range [0, 1]
norm <- function(x) {
    apply(x, 2, function(y){(y-min(y))/(max(y)-min(y))})
}

bluecol <- colorRamp(c("#3366EE", "#AABBFF", "#DDDDFF"))(norm(iris))
bluecol <- rgb(bluecol[, 1], bluecol[, 2], bluecol[, 3], max=255)

tt <- ttheme_default(core=list(bg_params=list(fill=bluecol)))

g <- tableGrob(iris, theme=tt)
g <- gtable_add_grob(g,
    grobs = rectGrob(gp = gpar(fill = NA, lwd = 2)),
    t = 2, b = nrow(g), l = 1, r = ncol(g))
g <- gtable_add_grob(g,
    grobs = rectGrob(gp = gpar(fill = NA, lwd = 2)),
    t = 1, l = 1, r = ncol(g))
grid.draw(g)

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