基础中的渐变图例 [英] Gradient legend in base

问题描述

我之前曾问过要在基础图形中创建n值的渐变(

Earlier I asked about creating a gradient of n values in base graphics (LINK). Now I'd like to create a gradient legend that goes with it. My ideal would be something like ggplot2's gradient legends:

以下是一些与我正在使用的代码相似的代码:

Here's some code similar to what I'm working with:

colfunc <- colorRampPalette(c("red", "blue"))
plot(1:20, 1:20, pch = 19, cex=2, col = colfunc(20))

推荐答案

下面是一个示例，该示例说明了如何使用grDevices和layout中的rasterImage从第一原理构建图例

Here is an example of how to build a legend from first principles using rasterImage from grDevices and layout to split the screen

layout(matrix(1:2,ncol=2), width = c(2,1),height = c(1,1))
plot(1:20, 1:20, pch = 19, cex=2, col = colfunc(20))

legend_image <- as.raster(matrix(colfunc(20), ncol=1))
plot(c(0,2),c(0,1),type = 'n', axes = F,xlab = '', ylab = '', main = 'legend title')
text(x=1.5, y = seq(0,1,l=5), labels = seq(0,1,l=5))
rasterImage(legend_image, 0, 0, 1,1)

这篇关于基础中的渐变图例的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！