Re: [R] Plotting two regression lines on one graph
Since you have provided no executable data and not even a clear enough description of the data to offer advice regarding approaches or pitfalls, I will use the example in glm's help page: counts <- c(18,17,15,20,10,20,25,13,12) outcome <- gl(3,1,9) treatment <- gl(3,3) glm.D93r <- glm(counts ~ outcome, family=poisson()) plot(x=as.numeric(as.character(outcome)), y=counts, type="p") #need to convert from factor to ge points lines(1:3, c(exp(3.045), exp(3.0445 -0.4543), exp(3.0445 -0.2930) ) ) #the default link for poisson is log, so you need to transform back to the original scale to predict counts. On Jun 7, 2009, at 11:36 PM, Jo Stringer wrote: I have fitted two glms assuming a poisson distribution which are: fit1 <- glm(Aids ~ Year, data=aids, family=poisson()) fit2 <- glm(Aids ~ Year+I(Year^2), data=aids, family=poisson()) I am trying to work out how to represent the fitted regression curves of fit1 and fit2 on the one graph. I have tried: graphics.off() plot(Aids ~ Year, data = aids) line(glm(Aids ~ Year, data=aids, family=poisson())) line(glm(Aids ~ Year+I(Year^2), data=aids, family=poisson())) but this does not work. Can anyone help me? David Winsemius, MD Heritage Laboratories West Hartford, CT __ 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.
Re: [R] Plotting two regression lines on one graph
Hi Jo,
Next time try prepare a reproducible code.
You have several ways of do that (see Dylan Beaudette) and give a look
below.
x<-1:100
y<-7+x*(sqrt(x*runif(100)))
plot(y~x)
mod1<-glm(y~x)
mod2<-glm(y~x+I(x*x))
curve(mod1$coef[1]+mod1$coef[2]*x, col="red", add=T, lwd=3)
curve(mod2$coef[1]+mod2$coef[2]*x+mod2$coef[3]*x*x, col="green", add=T,
lwd=3)
cheers
milton
On Sun, Jun 7, 2009 at 11:36 PM, Jo Stringer wrote:
> Hi!
>
>
> I have fitted two glms assuming a poisson distribution which are:
>
> fit1 <- glm(Aids ~ Year, data=aids, family=poisson())
>
> fit2 <- glm(Aids ~ Year+I(Year^2), data=aids, family=poisson())
>
>
> I am trying to work out how to represent the fitted regression curves of
> fit1 and fit2 on the one graph. I have tried:
>
> graphics.off()
>
> plot(Aids ~ Year, data = aids)
>
>
> line(glm(Aids ~ Year, data=aids, family=poisson()))
> line(glm(Aids ~ Year+I(Year^2), data=aids, family=poisson()))
>
> but this does not work.
>
> Can anyone help me?
>
> Thanks
>
> Jo
>
> BSES Limited Disclaimer
>
>
>
>
> This email and any files transmitted with it are confide...{{dropped:15}}
>
> __
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
[[alternative HTML version deleted]]
__
R-help@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] Plotting two regression lines on one graph
One approach to this is generating a representative sequence of your
x-variable(s) with seq() or expand.grid(). Next use the predict()
function to make predictions from your glm object along the sequence.
Finally, plot the predictions vs. the new sequence. Putting everything
into a dataframe helps.
# generate some data:
x <- rnorm(10)
y <- x * 2 + rnorm(10, sd=0.5)
# plot
plot(y ~ x)
# generate linear model:
l <- lm(y ~ x)
# generate sequence along x-var
# and predictions
d <- data.frame(x.new=seq(from=-1.5, to=1.2, by=0.1))
d$y.new <- predict(l, data.frame(x=d$x.new))
# add to plot:
lines(y.new ~ x.new, data=d, lwd=2)
Cheers,
Dylan
On Sun, Jun 7, 2009 at 8:36 PM, Jo Stringer wrote:
> Hi!
>
>
> I have fitted two glms assuming a poisson distribution which are:
>
> fit1 <- glm(Aids ~ Year, data=aids, family=poisson())
>
> fit2 <- glm(Aids ~ Year+I(Year^2), data=aids, family=poisson())
>
>
> I am trying to work out how to represent the fitted regression curves of fit1
> and fit2 on the one graph. I have tried:
>
> graphics.off()
>
> plot(Aids ~ Year, data = aids)
>
>
> line(glm(Aids ~ Year, data=aids, family=poisson()))
> line(glm(Aids ~ Year+I(Year^2), data=aids, family=poisson()))
>
> but this does not work.
>
> Can anyone help me?
>
> Thanks
>
> Jo
>
> BSES Limited Disclaimer
>
>
>
> This email and any files transmitted with it are confide...{{dropped:15}}
>
> __
> 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.
>
__
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.
[R] Plotting two regression lines on one graph
Hi!
I have fitted two glms assuming a poisson distribution which are:
fit1 <- glm(Aids ~ Year, data=aids, family=poisson())
fit2 <- glm(Aids ~ Year+I(Year^2), data=aids, family=poisson())
I am trying to work out how to represent the fitted regression curves of fit1
and fit2 on the one graph. I have tried:
graphics.off()
plot(Aids ~ Year, data = aids)
line(glm(Aids ~ Year, data=aids, family=poisson()))
line(glm(Aids ~ Year+I(Year^2), data=aids, family=poisson()))
but this does not work.
Can anyone help me?
Thanks
Jo
BSES Limited Disclaimer
This email and any files transmitted with it are confide...{{dropped:15}}
__
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.
