John,

you need ylim for that capability.

Rich

tmp <- read.table(textConnection("
     Slope PctCont PctCat PctTTst
  0.05     7.4    5.6     6.3
  0.10    17.7   11.3    13.3
  0.15    32.7   18.7    25.6
  0.20    53.3   27.5    40.2
  0.25    72.1   41.2    54.5
  0.30    85.5   52.9    70.8
  0.35    93.9   65.2    83.6
  0.40    97.0   73.6    89.9
  0.45    99.7   84.8    96.5
  0.50    99.9   90.1    98.4
  0.55   100.0   93.2    99.7
  0.60   100.0   97.3    99.8
  0.65   100.0   98.8   100.0
  0.70   100.0   99.4   100.0
  0.75   100.0   99.8   100.0
  0.80   100.0   99.7   100.0
  0.85   100.0  100.0   100.0
  0.90   100.0  100.0   100.0
  0.95   100.0  100.0   100.0
  1.00   100.0  100.0   100.0
"), header=TRUE)
par(mfrow=c(1,1))
plot(tmp[,"Slope"],tmp[,"PctCont"],type="b",yaxp=c(0,100,10), ylim=c(0,100),
ylab="prevent overlap")
par(new=TRUE)
plot(tmp[,"Slope"],tmp[,"PctCat"],type="b",yaxp=c(0,100,10), ylim=c(0,100),
ylab="")
par(new=TRUE)
plot(tmp[,"Slope"],tmp[,"PctTTst"],type="b",yaxp=c(0,100,10), ylim=c(0,100),
ylab="")




On Fri, Apr 22, 2011 at 11:55 PM, John Sorkin
<jsorkin@grecc.umaryland.edu>wrote:

> R 2.10
> Windows 7
>
> I am trying to plot three graphs on top of each other. I need to have the
> axises perfectly aligned. For some reason the ticks on the y axes are
> slightly off so they do not perfectly align. Can someone tell me how I can
> get the to overlay each other perfectly? I thought the yaxp parameter would
> solve my problem, but it does not. My data and code follows:

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