如何绘制2个不同的y轴? [英] How can I plot with 2 different y-axes?

问题描述

我想在R中叠加两个散点图，以便每组点都有其自己的(不同的)y轴(即，在图的位置2和4上)，但这些点看起来都叠加在同一图上. /p>

是否可以通过plot来做到这一点?

编辑显示问题的示例代码

# example code for SO question
y1 <- rnorm(10, 100, 20)
y2 <- rnorm(10, 1, 1)
x <- 1:10
# in this plot y2 is plotted on what is clearly an inappropriate scale
plot(y1 ~ x, ylim = c(-1, 150))
points(y2 ~ x, pch = 2)

解决方案

更新:R Wiki上后退机器

同一图上的两个不同的y轴

(某些资料最初由Daniel Rajdl于2006/03/31 15:26发表)

请注意，在极少数情况下，在同一图上使用两个不同的比例是合适的.容易误导图形的观看者.检查以下两个示例和对此问题的评论( example1 ， example2 junk_charts/"rel =" noreferrer>垃圾图表)，以及 Stephen Few的这篇文章(结论是我当然不能一劳永逸地得出结论，双刻度轴图永远都不会有用；只是我无法想到一种情况，可以根据其他情况来保证它们的存在. ，更好的解决方案.")另请参见此卡通中的第4点.

如果确定的话，基本方法是创建第一个图，设置par(new=TRUE)以防止R清除图形设备，并用axes=FALSE创建第二个图(并将xlab和ylab设置为为空白– ann=FALSE也应该起作用)，然后使用axis(side=4)在右侧添加新轴，并使用mtext(...,side=4)在右侧添加轴标签.这是一个使用少量虚构数据的示例:

set.seed(101)
x <- 1:10
y <- rnorm(10)
## second data set on a very different scale
z <- runif(10, min=1000, max=10000) 
par(mar = c(5, 4, 4, 4) + 0.3)  # Leave space for z axis
plot(x, y) # first plot
par(new = TRUE)
plot(x, z, type = "l", axes = FALSE, bty = "n", xlab = "", ylab = "")
axis(side=4, at = pretty(range(z)))
mtext("z", side=4, line=3)

plotrix软件包中的

twoord.plot()与latticeExtra软件包中的doubleYScale()一样自动执行此过程.

另一个示例(改编自Robert W. Baer的R邮件列表帖子):

## set up some fake test data
time <- seq(0,72,12)
betagal.abs <- c(0.05,0.18,0.25,0.31,0.32,0.34,0.35)
cell.density <- c(0,1000,2000,3000,4000,5000,6000)

## add extra space to right margin of plot within frame
par(mar=c(5, 4, 4, 6) + 0.1)

## Plot first set of data and draw its axis
plot(time, betagal.abs, pch=16, axes=FALSE, ylim=c(0,1), xlab="", ylab="", 
   type="b",col="black", main="Mike's test data")
axis(2, ylim=c(0,1),col="black",las=1)  ## las=1 makes horizontal labels
mtext("Beta Gal Absorbance",side=2,line=2.5)
box()

## Allow a second plot on the same graph
par(new=TRUE)

## Plot the second plot and put axis scale on right
plot(time, cell.density, pch=15,  xlab="", ylab="", ylim=c(0,7000), 
    axes=FALSE, type="b", col="red")
## a little farther out (line=4) to make room for labels
mtext("Cell Density",side=4,col="red",line=4) 
axis(4, ylim=c(0,7000), col="red",col.axis="red",las=1)

## Draw the time axis
axis(1,pretty(range(time),10))
mtext("Time (Hours)",side=1,col="black",line=2.5)  

## Add Legend
legend("topleft",legend=c("Beta Gal","Cell Density"),
  text.col=c("black","red"),pch=c(16,15),col=c("black","red"))

相似的配方可用于叠加不同类型的图-条形图，直方图等.

I would like superimpose two scatter plots in R so that each set of points has its own (different) y-axis (i.e., in positions 2 and 4 on the figure) but the points appear superimposed on the same figure.

Is it possible to do this with plot?

Edit Example code showing the problem

# example code for SO question
y1 <- rnorm(10, 100, 20)
y2 <- rnorm(10, 1, 1)
x <- 1:10
# in this plot y2 is plotted on what is clearly an inappropriate scale
plot(y1 ~ x, ylim = c(-1, 150))
points(y2 ~ x, pch = 2)

解决方案

update: Copied material that was on the R wiki at http://rwiki.sciviews.org/doku.php?id=tips:graphics-base:2yaxes, link now broken: also available from the wayback machine

Two different y axes on the same plot

(some material originally by Daniel Rajdl 2006/03/31 15:26)

Please note that there are very few situations where it is appropriate to use two different scales on the same plot. It is very easy to mislead the viewer of the graphic. Check the following two examples and comments on this issue (example1, example2 from Junk Charts), as well as this article by Stephen Few (which concludes "I certainly cannot conclude, once and for all, that graphs with dual-scaled axes are never useful; only that I cannot think of a situation that warrants them in light of other, better solutions.") Also see point #4 in this cartoon ...

If you are determined, the basic recipe is to create your first plot, set par(new=TRUE) to prevent R from clearing the graphics device, creating the second plot with axes=FALSE (and setting xlab and ylab to be blank – ann=FALSE should also work) and then using axis(side=4) to add a new axis on the right-hand side, and mtext(...,side=4) to add an axis label on the right-hand side. Here is an example using a little bit of made-up data:

set.seed(101)
x <- 1:10
y <- rnorm(10)
## second data set on a very different scale
z <- runif(10, min=1000, max=10000) 
par(mar = c(5, 4, 4, 4) + 0.3)  # Leave space for z axis
plot(x, y) # first plot
par(new = TRUE)
plot(x, z, type = "l", axes = FALSE, bty = "n", xlab = "", ylab = "")
axis(side=4, at = pretty(range(z)))
mtext("z", side=4, line=3)

twoord.plot() in the plotrix package automates this process, as does doubleYScale() in the latticeExtra package.

Another example (adapted from an R mailing list post by Robert W. Baer):

## set up some fake test data
time <- seq(0,72,12)
betagal.abs <- c(0.05,0.18,0.25,0.31,0.32,0.34,0.35)
cell.density <- c(0,1000,2000,3000,4000,5000,6000)

## add extra space to right margin of plot within frame
par(mar=c(5, 4, 4, 6) + 0.1)

## Plot first set of data and draw its axis
plot(time, betagal.abs, pch=16, axes=FALSE, ylim=c(0,1), xlab="", ylab="", 
   type="b",col="black", main="Mike's test data")
axis(2, ylim=c(0,1),col="black",las=1)  ## las=1 makes horizontal labels
mtext("Beta Gal Absorbance",side=2,line=2.5)
box()

## Allow a second plot on the same graph
par(new=TRUE)

## Plot the second plot and put axis scale on right
plot(time, cell.density, pch=15,  xlab="", ylab="", ylim=c(0,7000), 
    axes=FALSE, type="b", col="red")
## a little farther out (line=4) to make room for labels
mtext("Cell Density",side=4,col="red",line=4) 
axis(4, ylim=c(0,7000), col="red",col.axis="red",las=1)

## Draw the time axis
axis(1,pretty(range(time),10))
mtext("Time (Hours)",side=1,col="black",line=2.5)  

## Add Legend
legend("topleft",legend=c("Beta Gal","Cell Density"),
  text.col=c("black","red"),pch=c(16,15),col=c("black","red"))

Similar recipes can be used to superimpose plots of different types – bar plots, histograms, etc..

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