[R] plot and lm (2)

[Antonio Olinto]

Thanks for your reply Nassar.

What I really want is to overlay (like add=TRUE) the plots 1 and 2. With
plots "at the same screen" I meant overlaid and not one beside the other,
i.e., only one plot with all the points (1 to 10) in blue (or any other
color), the points 5 to 9 in red and a regression line from points 5 to 9.

Best regards,

Antonio Olinto

----- Original Message -----
From: "Rashid Nassar" <rnassar at duke.edu>
To: "Antonio Olinto" <aolinto at bignet.com.br>
Sent: Sunday, September 23, 2001 2:20 PM
Subject: Re: [R] plot and lm


> One way to do this (if I understand you correctly):
>
> > qu
>     x   y
> 1   1 1.0
> 2   2 2.0
> 3   3 3.0
> 4   4 4.0
> 5   5 4.4
> 6   6 4.1
> 7   7 3.2
> 8   8 3.1
> 9   9 2.4
> 10 10 2.7
>
> > qu$group <- c(rep(1,4),rep(2,5), 1)
> > attach(qu)
> > opar <- par(mfcol=c(1,2), pty="s")   # use pty="m" (default) if you
>                                        #don't want square plots.
> > plot(x,y, col="blue", pch=19)
> > title("Plot 1")
> > plot(x[group==2], y[group==2], col="red", pch=19, main="Plot 2")
> > abline(lm(y ~ x, data=qu, subset=group==2), col="red")
> > detach(qu)
> > par(opar)
>
>
> I hope this helps.
>
> Rashid Nassar
>
> On Sun, 23 Sep 2001, Antonio Olinto wrote:
>
> > Date: Sun, 23 Sep 2001 13:16:46 -0300
> > From: Antonio Olinto <aolinto at bignet.com.br>
> > To: R-help <r-help at stat.math.ethz.ch>
> > Subject: [R] plot and lm
> >
> > Hello R-list,
> >
> >  I'm trying to make a scatter plot with two dependent variables and a
> > regression line only for one "y", but I'm having some problems. Well, I
will
> > explain better what I'm doing - it's a method used to estimate the total
> > mortality rate in fish stocks.
> >
> > Suppose a I have the following data (dat):
> >
> > > dat
> >       x     y
> > 1    1   1.0
> > 2    2   2.0
> > 3    3   3.0
> > 4    4   4.0
> > 5    5   4.4
> > 6    6   4.1
> > 7    7   3.2
> > 8    8   3.1
> > 9    9   2.4
> > 10 10  2.7
> >
> > With plot(x,y col="blue", pch=19) and identify(x,y) I can identify the
blue
> > points that follow a descendent trend (negative slope). They are points
5 to
> > 9. Let's call this plot 1.
> >
> > With dat2 <- dat[c(5:9),] I can make another data.frame and and using
> > attach(dat2), plot(x,y, col="red", pch=19), reg <- lm(y~x) and
abline(reg) I
> > have another plot (plot 2) with red points and the regression line.
> >
> > I would like to have in one plot all the points (1 to 10) in blue, the
> > points 5 to 9 in red and a regression line from points 5 to 9. In other
> > words, plots 1 and 2 at the same screen. I'm sure that it's possible to
do
> > this plot but after several attempts I decide to ask for your help in
this
> > Sunday morning.
> >
> > Thanks for any suggestion,
> >
> > Antonio Olinto
> > Fisheries Institute
> > Sao Paulo - BRAZL
> >
> >
>
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> >

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