R 代码不保存绘图图像 [英] R code doesn't save plot image

问题描述

以下代码生成图像:

library(latticeExtra)
x=runif(40)
y=runif(40)
z=runif(40)
png(filename=paste(i,".png",sep=""))
levelplot(z ~ x + y, panel = panel.levelplot.points, col.regions = rainbow(50))
dev.off()

但是下面的代码没有.为什么?

But the following code does not. Why?

library(latticeExtra)
for(i in seq(1,5)) {
    x=runif(40)
    y=runif(40)
    z=runif(40)
    png(filename=paste(i,".png",sep=""))
    levelplot(z ~ x + y, panel = panel.levelplot.points, col.regions = rainbow(50))
    dev.off()
}

推荐答案

好吧，我会写下我在评论中写的内容作为答案.

Well, I'll just write what I wrote in the comments as an answer.

在您自己的循环或函数中绘制 lattice 或 ggplot2 图时，您必须明确地print lattice>/ggplot2 绘图

When plotting lattice or ggplot2 plots inside your own loops or functions, you have to explicitly print the lattice/ggplot2 plots

试试这个:

library(latticeExtra)
png(filename="plot_%02d.png")
for(i in seq(1,5)) {
    x=runif(40)
    y=runif(40)
    z=runif(40)
    # Assign your lattice plot to myPlot
    myPlot <- levelplot(z ~ x + y, panel = panel.levelplot.points, col.regions = rainbow(50))
    print(myPlot)
}
dev.off()

我相信 R 常见问题的这一部分在这里是相关的:7.22 为什么格子/格子图形不起作用?

I believe this part of the R FAQs is relevant here: 7.22 Why do lattice/trellis graphics not work?

我将 png 代码更改为位于循环之前，并将 dev.off() 置于循环之外.

I changed the png code to come before the loop and placed dev.off() outside of the loop.

png(filename="plot_%02d.png") 将第一个图保存为 plot_01.png，第二个图保存为 plot_02.png 等

png(filename="plot_%02d.png") will save the first plot as plot_01.png, the second plot as plot_02.png, etc.

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