R help - Nov 2005 - newbie graphics question: Two density plots in same frame ?

I swear I've scoured the help files and several texts before posting
what feels like a dumb newbie question.  
 
How can I draw two kernel density plots in the same frame ? I have
similar variables in two separate data frames, and I would like to show
their two histograms/densities in a single picture.  Same units, scale,
range for both, so I'm simply trying to draw one and then add the other
to the picture.  Nothin' fancy.
 

Bill Alpert

Sr. Editor

Barron's

212.416.2742

william.alpert@barrons.com

 

 

	[[alternative HTML version deleted]]

Here's a function that you can customize to fit your needs. lst is a named
list.

multicomp <- function(lst)
{
clr <-
c("darkgreen","red","blue","brown","magenta")
alldens <- lapply(lst,function(x) {density(x,from=min(x),to=max(x))})
allx <- sapply(alldens,function(d) {d$x})
ally <- sapply(alldens,function(d) {d$y})
plot(allx,ally,type="n")
for (i in 1:length(lst)) {
	lines(alldens[[i]]$x,alldens[[i]]$y,lty=i,col=clr[i],lwd=3)
	}
legend("topright",xjust=1,legend=names(lst),lwd=3,lty=1:length(lst),col=head(clr,length(lst)))
}
#---------------
toplot <- list(var1=dfr1$var,var2=dfr2$var)
multicomp(toplot)

> -----Original Message-----
> From: Alpert, William [mailto:William.Alpert at barrons.com]
> Sent: Thursday, November 03, 2005 11:45 AM
> To: r-help at stat.math.ethz.ch
> Subject: [R] newbie graphics question: Two density plots in
> same frame ?
>
>
> I swear I've scoured the help files and several texts before posting
> what feels like a dumb newbie question.
>
> How can I draw two kernel density plots in the same frame ? I have
> similar variables in two separate data frames, and I would
> like to show
> their two histograms/densities in a single picture.  Same
> units, scale,
> range for both, so I'm simply trying to draw one and then add
> the other
> to the picture.  Nothin' fancy.
>
>
> Bill Alpert
>
> Sr. Editor
>
> Barron's
>
> 212.416.2742
>
> william.alpert at barrons.com
>
>
>
>
>
> 	[[alternative HTML version deleted]]
>
> ______________________________________________
> R-help at 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
>

To plot two Kernel densities you can use matplot:

x1<-density(rnorm(100))
x2<-density(rnorm(100))
matplot(cbind(x1$y,x2$y), type="l")


Or if both distributions are really very similar and you don't have to 
adjust the axes you can simply use
plot(x1)
lines(x2, col="red")


Finally if you want to have two histograms in the same picture (I would not 
recomend it tough since the distributions are similar so the overlapping 
will make it very messy) you can use the argument "add" within hist

hist(rnorm(100), col="red")
hist(rnorm(100), col="blue", add=T)

I hope this helps

Francisco
>From: "Alpert, William" <William.Alpert at barrons.com>
>To: <r-help at stat.math.ethz.ch>
>Subject: [R] newbie graphics question: Two density plots in same frame ?
>Date: Thu, 3 Nov 2005 11:45:21 -0500
>
>I swear I've scoured the help files and several texts before posting
>what feels like a dumb newbie question.
>
>How can I draw two kernel density plots in the same frame ? I have
>similar variables in two separate data frames, and I would like to show
>their two histograms/densities in a single picture.  Same units, scale,
>range for both, so I'm simply trying to draw one and then add the other
>to the picture.  Nothin' fancy.
>
>
>Bill Alpert
>
>Sr. Editor
>
>Barron's
>
>212.416.2742
>
>william.alpert at barrons.com
>
>
>
>
>
>	[[alternative HTML version deleted]]
>
>______________________________________________
>R-help at 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

On 11/3/05, Alpert, William <William.Alpert at barrons.com>
wrote:
> I swear I've scoured the help files and several texts before posting
> what feels like a dumb newbie question.
>
> How can I draw two kernel density plots in the same frame ? I have
> similar variables in two separate data frames, and I would like to show
> their two histograms/densities in a single picture.  Same units, scale,
> range for both, so I'm simply trying to draw one and then add the other
> to the picture.  Nothin' fancy.
Using densityplot from lattice:

library(lattice)
d1 = data.frame(x = rnorm(100))
d2 = data.frame(x = rnorm(100, mean = 0.5))
densityplot(~d1$x + d2$x, plot.points = FALSE)

-Deepayan