Joe Trubisz wrote:
Hi...
Is this possible in R?
I have 2-sets of data, that were collected simultaneously using
2-different data acquisition schemes.
The x-values are the same for both.
The y-values have different ranges (16.4-37.5 using one method, 557-634
using another).
In theory, if you plot both plots on top of each other, the graphs should
overlap. The problem I'm having is trying to have to different sets of
y-values appear in the same graph, but scaled in the same vertical space.
I've seen this done in publications, but not sure if it can be done in R.
Here's a brute force graph with two sets of y-axis
# 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, 4) + 0.1)
# Plot first set of data and draw its axis
plot(time, betagal.abs, pch=16, axes=F, ylim=c(0,1), xlab="", ylab="",
type="b",col="black", main="Mike's test data")
axis(2, ylim=c(0,1),col="black")
mtext("Beta Gal Absorbance",side=2,line=2.5)
box()
# Allow a second plot on the same graph
par(new=T)
# Plot the second plot and put axis scale on right
plot(time, cell.density, pch=15, xlab="", ylab="", ylim=c(0,7000), axes=F,
type="b", col="red")
mtext("Cell Density",side=4,col="red",line=2.5)
axis(4, ylim=c(0,7000), col="red",col.axis="red")
# Draw the time axis
axis(1,pretty(range(time),10))
mtext("Time (Hours)",side=1,col="black",line=2.5)
# Add Legend
legend(5,7000,legend=c("Beta Gal","Cell
Density"),text.col=c("black","red"),pch=c(16,15),col=c("black","red"))
HTH,
Rob Baer
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