Creating multiple graphs based on one variable

From: Luc Villandre <villandl at dms.umontreal.ca>
Subject: Re: [R] Creating multiple graphs based on one variable
To: "Tim Clark" <mudiver1200 at yahoo.com>
Cc: r-help at r-project.org
Date: Tuesday, May 26, 2009, 4:01 AM
Tim Clark wrote:

Dear List,

I would like to create several graphs of similar

data.? I have x and y values for several different
individuals (in this case fish).? I would like to plot
the x and y values for each fish separately.? I can do
it using a for loop, but I think I should be using
"apply".? Please let me know what I am doing wrong, or
if there is a "better" way to do this.? What I have
is:

#Test data

dat<-data.frame(c(rep(1:10,4)),c(rep(1:10,4)),c(rep(c("Tony","Mike","Vicky","Fred"),each=10)))

names(dat)<-c("x","y","Name") 
#Create function to plot x and y
myplot<-function() plot(dat$x,dat$y)

#Apply the function to each of the names

par(mfcol=c(2,2))???apply(dat,2,myplot,by=dat$Name)
#Does not work - tried various versions

I would like separate plots for Tony, Mike, and

Vicky.? What is the best way to do this?? 

Thank!

Tim


Tim Clark
Department of Zoology University of Hawaii

mailing list

reproducible code.

???

Hi Tim,

I'm now rather fond of Hadley Wickham's ggplot2 package.
Its structure is most of the times intuitive and it does
yield nice-looking output.

In order to solve your problem, taking advantage of the
ggplot2 framework, you can simply use the following:

library(ggplot2) ;
## If you want all the curves to be on the same

plotting grid ;

p <- ggplot(dat, aes(x=x,y=y, group=Name)) ;
p + geom_line(aes(colour=Name)) ; ## Only one curve

will be visible since they are all superposed.

## If you want the curves to be on separate plotting

grids ;

p <- ggplot(dat, aes(x=x,y=y, group=Name)) ;
p <- p + geom_line(aes(colour=Name)) ;
p+facet_grid(. ~ Name) ;

Hope this helps,
-- *Luc Villandr?*
/Biostatistician
McGill University Health Center -
Montreal Children's Hospital Research Institute/