R help - Jun 2007 - ylab at the right hand of a plot with two y axes

When I try to plot two lines ( or scatterplots) with different scales, this
is what I have been doing:

Suppose: I have y1 and y2 in a very different scale

y1 = 1:100
y2 = c(100:1)*10

To plot them on top of each other  and denote by different colors: I have to
figure out the correct scale '10'  and corresponding tick.vector and
lables.
Then do:

plot(1:100, y1)   # I can have 'ylab' here for the left-hand side y
axis.
points(1:100, y2/10,col=2)
ytick.vector = seq(from=0,to=100,by=20)
ytick.label = as.character(seq(from=0,to=1000,by=200))
axis(4,at = ytick.vector,label = ytick.label,col=2,col.axis=2)

Two questions.

1. Are there easier ways to plot the y1, y2 w/o figuring out the correct
scaler, tick vectors, and labels in order to put them in one figure?
2. How to add additional 'ylab' to the right hand side y-axis of the
plot?
Thanks a lot!

-Young

	[[alternative HTML version deleted]]

Here are two ways:

## method 1
plot(1:100,y1)
par(new=TRUE)
plot(1:100,y2,xlab="",ylab="",col=2,axes=FALSE)
axis(4,col=2,col.axis=2)

## method 2
plot.new()
plot.window(xlim=c(1,100),ylim=range(y1))
points(1:100,y1)
axis(1)
axis(2)
title(xlab="x",ylab="y1")
plot.window(xlim=c(1,100),ylim=range(y2))
points(1:100,y2)
axis(4,col=2,col.axis=2)
box()



--- Young Cho <young.stat at gmail.com> wrote:
> When I try to plot two lines ( or scatterplots) with different scales, this
> is what I have been doing:
> 
> Suppose: I have y1 and y2 in a very different scale
> 
> y1 = 1:100
> y2 = c(100:1)*10
> 
> To plot them on top of each other  and denote by different colors: I have
> to
> figure out the correct scale '10'  and corresponding tick.vector
and
> lables.
> Then do:
> 
> plot(1:100, y1)   # I can have 'ylab' here for the left-hand side y
axis.
> points(1:100, y2/10,col=2)
> ytick.vector = seq(from=0,to=100,by=20)
> ytick.label = as.character(seq(from=0,to=1000,by=200))
> axis(4,at = ytick.vector,label = ytick.label,col=2,col.axis=2)
> 
> Two questions.
> 
> 1. Are there easier ways to plot the y1, y2 w/o figuring out the correct
> scaler, tick vectors, and labels in order to put them in one figure?
> 2. How to add additional 'ylab' to the right hand side y-axis of
the plot?
> Thanks a lot!
> 
> -Young
> 
> 	[[alternative HTML version deleted]]
> 
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