-----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 Thanks for your help!!
I appreciate, now it works perfectly. Lothar Rubusch Duncan Murdoch wrote: > On 9/25/2006 1:56 PM, Lothar Botelho-Machado wrote: >> Hey R-Comunity, >> >> >> I'd like to print out an histogram of some experimental data and add a >> smooth curve of a normal distribution with an ideally generated >> population having the same mean and standard deviation like the >> experimental data. >> >> >> The experimental data is set as vector x and its name is set to >> group.name. I paint the histogram as follows: >> >> hist(data, freq=FALSE, col="lightgrey", ylab="Density", xlab=group.name) >> >> >> >> First I did the normal distribution curve this way: >> >> lines(x, dnorm(x, mean=mean(x), sd=sd(x)), type="l", lwd=2) >> >> This curve just uses as many values as there are in x. When using small >> amounts of sample populations the curve looks really shaky. > > This is generally the right way to do it, but you likely want to use a > different variable for the first two occurrences of x, e.g. > > x0 <- seq(from=min(x), to=max(x), len=200) > lines(x0, dnorm(x0, mean=mean(x), sd=sd(x)), type="l", lwd=2) > > Duncan Murdoch > >> >> >> I tried this one using a high level plot function as well: >> >> curve(dnorm, n=10000, add=TRUE, xlim=range(x)) >> >> The advantage is, now I can set an ideal population of 10000 to get the >> ideal curve really smooth. But the big disadvantage is, I don't know how >> to add "mean=mean(x), sd=sd(x)" arguments to it? It says that it can't >> mix high level with low level plot functions when I try to set some kind >> of parameter like "n=10000" to the low level function, it says that >> there ain't enough x values. >> >> So my question is, how to get a smooth curve placed of dnorm over an >> histogram of sample data, ideally by using the curve method? >> >> >> TIA, >> Lothar Rubusch >> >> ______________________________________________ >> R-help@stat.math.ethz.ch 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. > > -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.5 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org iD8DBQFFGEVAHRf7N9c+X7sRAtRoAJ97ft75u1etTac3Daiti1u2mlyRWgCeIAAK 81WfyDGzDdWDm11MwPiDKIA= =W2m9 -----END PGP SIGNATURE----- ______________________________________________ R-help@stat.math.ethz.ch 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.