Re: [R] how do I plot a regression curve with the data?
Ken Ervin wrote:
I have a data set of 6 or so ordered pairs, and I've been able to graph
them and have decided to use a high-order polynomial regression. I've
used the following piece of code:
regression - function(x,y) {
x - c(insert_numbers_here)
y - c(insert_other_numbers_here)
fit - lm(y ~ x + I(x^2) + I(x^3) + I(x^4) + I(x^5) + I(x^6) + I(x^7)
+ I(x^8) + I(x^9))
summary(fit)
This gives me the coefficients for the regression very nicely, but I
would like to plot both the data and the regression curve together. How
do I plot that regression curve as a function, and can I put it on the
same set of axes as my data scatter plot?
Are you sure that fitting such a high-degree polynomial makes
sense? Is there any theory to support the model? If you really
want to do this, then use predict.lm():
## with xmin, xmax as the limits of your scatterplot
xx - seq(xmin, xmax, length=51)
yy - predict(fit, newdata=list(x=xx))
lines(xx, yy) ## add to scatterplot
-Peter Ehlers
Thanks in advance for your help!
-KE
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Re: [R] how do I plot a regression curve with the data?
?curve
regards,
Tom
Ken Ervin schrieb:
I have a data set of 6 or so ordered pairs, and I've been able to graph
them and have decided to use a high-order polynomial regression. I've
used the following piece of code:
regression - function(x,y) {
x - c(insert_numbers_here)
y - c(insert_other_numbers_here)
fit - lm(y ~ x + I(x^2) + I(x^3) + I(x^4) + I(x^5) + I(x^6) + I(x^7)
+ I(x^8) + I(x^9))
summary(fit)
This gives me the coefficients for the regression very nicely, but I
would like to plot both the data and the regression curve together. How
do I plot that regression curve as a function, and can I put it on the
same set of axes as my data scatter plot?
Thanks in advance for your help!
-KE
__
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.
Re: [R] how do I plot a regression curve with the data?
On Wed, Oct 28, 2009 at 9:23 AM, Tom Gottfried tom.gottfr...@wzw.tum.de wrote:
?curve
regards,
Tom
and I was in the process of writing a curve example when I noticed Tom
sent this. Here it is:
set.seed(777)
x - runif(100, 0, 100)
y - 10*x + x^2 - .01*x^3 + rnorm(100, 0, 500)
fit - lm(y ~ x + I(x^2) + I(x^3))
B - coef(fit)
plot(x, y)
curve(10*x + x^2 - .01*x^3, col = 4, lty = 4,
lwd = 2, add = TRUE)
curve(B[1] + B[2]*x + B[3]*x^2 + B[4]*x^3, col = 2,
lty = 2, lwd = 2, add = TRUE)
legend('topleft', c('truth', 'fit'), lty = c(4, 2),
col = c(4, 2), lwd = 2)
btw, it's not possible to fit a 9th-degree polynomial model with lm
based on only '6 or so ordered pairs' (assuming that means 6 data
points). A 5th degree polynomial would be a direct interpolater.
hth,
Kingsford
Ken Ervin schrieb:
I have a data set of 6 or so ordered pairs, and I've been able to graph
them and have decided to use a high-order polynomial regression. I've
used the following piece of code:
regression - function(x,y) {
x - c(insert_numbers_here)
y - c(insert_other_numbers_here)
fit - lm(y ~ x + I(x^2) + I(x^3) + I(x^4) + I(x^5) + I(x^6) + I(x^7)
+ I(x^8) + I(x^9))
summary(fit)
This gives me the coefficients for the regression very nicely, but I
would like to plot both the data and the regression curve together. How
do I plot that regression curve as a function, and can I put it on the
same set of axes as my data scatter plot?
Thanks in advance for your help!
-KE
__
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-help@r-project.org mailing list
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PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
and provide commented, minimal, self-contained, reproducible code.
Re: [R] how do I plot a regression curve with the data?
Hi Ken,
Perhaps something like
plot(x,y)
lines(sort(x), fit$fitted.values[order(x)])
should do what I think you want. I think you have to be a bit careful
on the ordering of the fitted values so that they match up with the
order of the x variable, otherwise you get an odd looking line plot.
Regards,
Andrew
On Oct 28, 5:42 am, Ken Ervin ervinj...@gmail.com wrote:
I have a data set of 6 or so ordered pairs, and I've been able to graph
them and have decided to use a high-order polynomial regression. I've
used the following piece of code:
regression - function(x,y) {
x - c(insert_numbers_here)
y - c(insert_other_numbers_here)
fit - lm(y ~ x + I(x^2) + I(x^3) + I(x^4) + I(x^5) + I(x^6) +
I(x^7) + I(x^8) + I(x^9))
summary(fit)
This gives me the coefficients for the regression very nicely, but I
would like to plot both the data and the regression curve together. How
do I plot that regression curve as a function, and can I put it on the
same set of axes as my data scatter plot?
Thanks in advance for your help!
-KE
__
r-h...@r-project.org mailing listhttps://stat.ethz.ch/mailman/listinfo/r-help
PLEASE do read the posting guidehttp://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.
