[R] plot two graphs with different length of data

[Jim Lemon]

Eric Hu wrote:
> Hi I am trying to plot two data set in the same picture window without
> overlapping with each other. I am using the format plot(x1,y1,x2,y2)
> but get the following error message:
> 
> 
>>plot(as.numeric(r0[,4]),as.numeric(r0[,7]),as.numeric(r0[,4]),as.numeric(r0[,7][ind[,1]]))
> 
> Error in plot.window(xlim, ylim, log, asp, ...) :
>         invalid 'ylim' value
> 
> Can anyone tell me what went wrong? Thanks.

plot is probably interpreting one of your data vectors as the ylim 
argument. If you want to plot multiple data series of different lengths, 
it is probably simplest to use points() (or lines()) after plotting the 
first one. For an example of this, see:

http://cran.r-project.org/doc/contrib/Lemon-kickstart/kr_addat.html

Jim