R help - Jan 2008 - two histograms in the same graph

Dear Contributors:

I have two vectors x and z, and I want to display the histograms of both
vectors in the same graph, x in red bars, z in blue bars.
If you have any clue on how to do that, I will be very glad to hear it!!!!!!
Thanks in advance again,

Juan Pablo Fededa

	[[alternative HTML version deleted]]

That's an easy one with ggplot2.

library(ggplot2)
dataset <- data.frame(variable = gl(2, 50, labels = c("x",
"z")), value
= c(runif(50), rnorm(50)))
ggplot(data = dataset, aes(x = value, fill = variable)) +
geom_histogram(position = "dodge") + scale_fill_manual(values =
c("red",
"blue"), guide = "tile") 

But I don't prefer to put two histograms into the same graphs. Making a
seperate histogram for each variable makes is easier to compare them. Or
you could use a density plot.

ggplot(data = dataset, aes(x = value, fill = variable)) +
geom_histogram() + facet_grid(variable ~ .) +  scale_fill_manual(values
= c("red", "blue"), guide = "tile") 
ggplot(data = dataset, aes(x = value, colour = variable)) +
geom_density() + scale_colour_manual(values = c("red",
"blue"), guide "line")

HTH,

Thierry

------------------------------------------------------------------------
----
ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature
and Forest
Cel biometrie, methodologie en kwaliteitszorg / Section biometrics,
methodology and quality assurance
Gaverstraat 4
9500 Geraardsbergen
Belgium 
tel. + 32 54/436 185
Thierry.Onkelinx op inbo.be 
www.inbo.be 

Do not put your faith in what statistics say until you have carefully
considered what they do not say.  ~William W. Watt
A statistical analysis, properly conducted, is a delicate dissection of
uncertainties, a surgery of suppositions. ~M.J.Moroney

-----Oorspronkelijk bericht-----
Van: r-help-bounces op r-project.org [mailto:r-help-bounces op r-project.org]
Namens Juan Pablo Fededa
Verzonden: donderdag 24 januari 2008 15:44
Aan: r-help
Onderwerp: [R] two histograms in the same graph

Dear Contributors:

I have two vectors x and z, and I want to display the histograms of both
vectors in the same graph, x in red bars, z in blue bars.
If you have any clue on how to do that, I will be very glad to hear
it!!!!!!
Thanks in advance again,

Juan Pablo Fededa

	[[alternative HTML version deleted]]

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On 1/24/2008 9:43 AM, Juan Pablo Fededa wrote:
> Dear Contributors:
> 
> I have two vectors x and z, and I want to display the histograms of both
> vectors in the same graph, x in red bars, z in blue bars.
> If you have any clue on how to do that, I will be very glad to hear
it!!!!!!
It's hard to design a graph like this that looks good, but it's easy to 
draw using add=TRUE:

x <- rnorm(1000)
y <- rnorm(1000, mean=1)
breaks <- pretty(range(c(x,y)), 20)
hist(x, breaks=breaks, col='red', main="Hist of x and y")
hist(y, breaks=breaks, add=TRUE, border='blue')

Duncan Murdoch

Juan Pablo Fededa wrote:
> Dear Contributors:
> 
> I have two vectors x and z, and I want to display the histograms of both
> vectors in the same graph, x in red bars, z in blue bars.
> If you have any clue on how to do that, I will be very glad to hear
it!!!!!!
> Thanks in advance again,
> 
Hi Juan,
The "multhist" function in the plotrix package can do this, although
you
might also want to look at "barp".

Jim

You might look at the method histbackback (back-to-back histograms) in  
package Hmisc.  At the time I looked at this package about a year ago,  
I could not get it working on my Mac, so I don't actually know what  
the results look like, but I have created them before in XLispStat and  
found them useful.  From posts I've seen more recently, I believe that  
whatever the problem I was encountering previously on the Mac has been  
resolved.

-David
> I have two vectors x and z, and I want to display the histograms of  
> both
> vectors in the same graph, x in red bars, z in blue bars.
> If you have any clue on how to do that, I will be very glad to hear  
> it!!!!!!
> Thanks in advance again,
----------------------------------
David Daniel
Associate Professor
University Statistics Center
New Mexico State University

ddaniel at nmsu.edu