[R] Re: plot and lm (2)

[Rashid Nassar]

I don't think I understand what you want to do: if you overlay them, then 
points 5:9 will show up as red, and 1:4 and 10 will show up as blue:

> group <- c(rep(1,4),rep(2,5), 1)
> plot(x,y, col="blue", pch=19)
> points(x[group==2], y[group==2], col="red", pch=19)
> abline(lm(y ~ x, data=qu, subset=group==2), col="red")

is that what you want to do?

best wishes,

Rashid Nassar


On Sun, 23 Sep 2001, Antonio Olinto wrote:

> Date: Sun, 23 Sep 2001 15:03:53 -0300
> From: Antonio Olinto <aolinto at bignet.com.br>
> To: R-help <r-help at stat.math.ethz.ch>, Rashid Nassar <rnassar at duke.edu>
> Subject: plot and lm (2)
> 
> 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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