Re: [R] How to plot a Quadratic Model?
see ?curve e.g. qftn <- function(x) 1 + 2*x - .1*x^2 curve(qftn, 0, 10) hth, Kingsford On Mon, Oct 5, 2009 at 9:42 AM, Juliano van Melis wrote: > Good day for all, > > I'm a beginner aRgonaut, thus I'm having a problem to plot a quadratic model > of regression in a plot. > First I wrote: > >>plot(Y~X) > > and then I tried: > >>abline(lm(Y~X+I(X^2)) > > but "abline" only uses the first two of three regression coefficients, thus > I tried: > >>line(lm(Y~X+I(X^2)) > > but a message error is showed ("insufficient observations"). > > Therefore, I want to know: how could I plot a quadratic line in my plot > graph? > > thanks! > > [[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. > __ 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 to plot a Quadratic Model?
I hardly use base graphics so I'm no help there. You can do this easily with ggplot2 though: library(ggplot2) X <- rnorm(100) Y <- rnorm(100) - X^2 qplot(x=X, y=Y, geom=c("point", "smooth"), method="lm", formula = y ~ poly(x, 2)) Note that X is not x and Y is not y in the sense that "formula = Y ~ poly(X, 2)" will not work (this tripped me up at first). qplot is taking x to mean "the first argument" (X in this case) and y to mean "the second argument" (Y in this case). -Ista On Mon, Oct 5, 2009 at 11:42 AM, Juliano van Melis wrote: > Good day for all, > > I'm a beginner aRgonaut, thus I'm having a problem to plot a quadratic model > of regression in a plot. > First I wrote: > >>plot(Y~X) > > and then I tried: > >>abline(lm(Y~X+I(X^2)) > > but "abline" only uses the first two of three regression coefficients, thus > I tried: > >>line(lm(Y~X+I(X^2)) > > but a message error is showed ("insufficient observations"). > > Therefore, I want to know: how could I plot a quadratic line in my plot > graph? > > thanks! > > [[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. > -- Ista Zahn Graduate student University of Rochester Department of Clinical and Social Psychology http://yourpsyche.org __ 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] How to plot a Quadratic Model?
Good day for all, I'm a beginner aRgonaut, thus I'm having a problem to plot a quadratic model of regression in a plot. First I wrote: >plot(Y~X) and then I tried: >abline(lm(Y~X+I(X^2)) but "abline" only uses the first two of three regression coefficients, thus I tried: >line(lm(Y~X+I(X^2)) but a message error is showed ("insufficient observations"). Therefore, I want to know: how could I plot a quadratic line in my plot graph? thanks! [[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.