Example code to produce a plot with two y axes using R. R is available free from the R CRAN repository.

`#`

# Author: James Goode

# Tendron Systems Ltd

#

# Example plot with two y axes

#

n = 150 # number of points

y1 = cumsum(rnorm(n))

y2 = cumsum(rnorm(n, mean=0.5))

```
```par(mai=c(.9, .8, .4, .8)) # margin size, in inches, c(bottom, left, top, right)

plot(1:n, y1, type="l", col="blue", xlab="X values", main="Plot with two axes")

par(new=TRUE)

plot(1:n, y2, type="l", ann=FALSE, yaxt="n")

axis(4)

legend(x="topleft", bty="y", lty=c(1,1), col=c("blue","red"),

legend=c("Line 1 (left y-axis)", "Line 2 (right y-axis)"))

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