
Dear Michael (and Davis), Your answer is not what I want to know. My question is to find any command to plot the data I got from the field; such as a set of (x,y) data ( I actually have these data) and together withe the derived ones . I brought these data to plot on x-y plane,  getting a graph showing some relation. Then, I wanted to find some linear relation, I would use least square method to solve having a simple function such as; y = ax + b, solving the a and b. So, I could plot a straight line using this function, or perhaps forecast some data of y which I know the value x. My problem is when I did a scatter plot by command "plot(x,y)", I got a graph. Whilst I plotted another graph using the above function the existing graph disappeared replaced be the latter function. Unfortunately, after searching a while to find the solution command, I can not find the command. I asked the question as to request some help not the example you shown. Any way, thanks for you effort. Tawee Mac OS10.7.3
 > From: michael.weylandt@gmail.com
> Date: Tue, 10 Apr 2012 23:31:08 -0400
> Subject: Re: [R] plot 2 graphs on the same x-y plane
> To: ohowow2007@hotmail.com
> CC: r-help@r-project.org
> 
> This is the same malformatted message you posted on R-SIG-Mac even
> after David specifically asked for clarification.... not to reward bad
> behavior, but perhaps this will enlighten:
> 
> # Minimal reproducible data!
> x <- runif(15, 0, 5)
> y <- 3*x - 2 + runif(15)
> 
> dat <- data.frame(x = x, y = y)
> rm(list = c("x", "y"))
> 
> # Base graphics plot using the formula interface
> plot(y ~ x, data = dat)
> abline(lm(y~x, data = dat), col = "red3", lwd = 2)
> 
> Alternatively
> 
> library(ggplot2)
> ggplot(dat, aes(x = x, y = y)) + geom_point() + stat_smooth(method =
> "lm", color = I("red3"))
> 
> which is perhaps overkill in this situation.
> 
> 
> Michael
> 
> On Tue, Apr 10, 2012 at 11:03 PM, Tawee Laoitichote
> <ohowow2007@hotmail.com> wrote:
> >
> >
> >
> >
> > hi,  I'm doing some data on least square curve fitting. What I like to have is to compare the scatter plot whilst having the fitting curve on the same coordinates. Any suggestting command besides plot(x,y).  TaweeMac OSX 10.7.3
> >        [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > https://stat.ethz.ch/mailman/listinfo/r-help
> > PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> > and provide commented, minimal, self-contained, reproducible code.
 		 	   		  
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