R help - Jan 2009 - Stacked barplot with two stacked bars besides each other

Hi,

I have a particular barplot I would like to generate, but I am having
trouble getting it to work.  What I would like is in effect two barplots
 with stacked bars merged into one.  For example,  I have two samples
(yoda1,yoda2) on which I measure whether two variables (var1,var2) are
present or absent for a number of measurements on that sample.
> var1 <- data.frame(yoda1=c(3,7), yoda2=c(1,9))
> var2 <- data.frame(yoda1=c(8,2), yoda2=c(5,5))
For each variable I can plot a barplot
> barplot(as.matrix(var1))
> barplot(as.matrix(var2))
I would like to join these together, so that for each sample there are
two stacked bars next to each other, one for var1 and the other for
var2.  I was thinking something like:
> barplot(list(as.matrix(var1),as.matrix(var2)))
would work, but it didn't.

Any suggestions you could make would be great.

Dan

-- 
**************************************************************
Daniel Brewer, Ph.D.

Institute of Cancer Research
Molecular Carcinogenesis
Email: daniel.brewer at icr.ac.uk
**************************************************************

The Institute of Cancer Research: Royal Cancer Hospital, a charitable Company
Limited by Guarantee, Registered in England under Company No. 534147 with its
Registered Office at 123 Old Brompton Road, London SW7 3RP.

This e-mail message is confidential and for use by the a...{{dropped:2}}

Try this:

barplot(cbind(as.matrix(var1), as.matrix(var2)), names.arg = LETTERS[1:4])

On Tue, Jan 20, 2009 at 8:28 AM, Daniel Brewer
<daniel.brewer@icr.ac.uk>wrote:
> Hi,
>
> I have a particular barplot I would like to generate, but I am having
> trouble getting it to work.  What I would like is in effect two barplots
>  with stacked bars merged into one.  For example,  I have two samples
> (yoda1,yoda2) on which I measure whether two variables (var1,var2) are
> present or absent for a number of measurements on that sample.
>
> > var1 <- data.frame(yoda1=c(3,7), yoda2=c(1,9))
> > var2 <- data.frame(yoda1=c(8,2), yoda2=c(5,5))
>
> For each variable I can plot a barplot
>
> > barplot(as.matrix(var1))
> > barplot(as.matrix(var2))
>
> I would like to join these together, so that for each sample there are
> two stacked bars next to each other, one for var1 and the other for
> var2.  I was thinking something like:
>
> > barplot(list(as.matrix(var1),as.matrix(var2)))
>
> would work, but it didn't.
>
> Any suggestions you could make would be great.
>
> Dan
>
> --
> **************************************************************
> Daniel Brewer, Ph.D.
>
> Institute of Cancer Research
> Molecular Carcinogenesis
> Email: daniel.brewer@icr.ac.uk
> **************************************************************
>
> The Institute of Cancer Research: Royal Cancer Hospital, a charitable
> Company Limited by Guarantee, Registered in England under Company No.
534147
> with its Registered Office at 123 Old Brompton Road, London SW7 3RP.
>
> This e-mail message is confidential and for use by the...{{dropped:20}}

On Tue, Jan 20, 2009 at 4:28 AM, Daniel Brewer <daniel.brewer at
icr.ac.uk> wrote:
> Hi,
>
> I have a particular barplot I would like to generate, but I am having
> trouble getting it to work.  What I would like is in effect two barplots
>  with stacked bars merged into one.  For example,  I have two samples
> (yoda1,yoda2) on which I measure whether two variables (var1,var2) are
> present or absent for a number of measurements on that sample.
>
>> var1 <- data.frame(yoda1=c(3,7), yoda2=c(1,9))
>> var2 <- data.frame(yoda1=c(8,2), yoda2=c(5,5))
I'd start by storing your data in a single data frame, with all
information explicit:

var1$row <- 1:2
var1$var <- "one"
var2$row <- 1:2
var2$var <- "two"

vars <- rbind(var1, var2)

library(reshape)
df <- melt(vars, id = c("var", "row"))
names(df)[3] <- "yoda"
df

(In reality you'd give the variables informative names based on your
study design)

Then you're in a position to better describe and control what you
want.  With the data in this form, you could then use the ggplot2
package to display it:

library(ggplot2)
qplot(yoda, value, data = df, fill = factor(row), geom="bar", stat
"identity", facets = ~ var)

This puts yoda on the x axis, colours the bars by the row and
separates the plot into two panels based on var.  It's trivial to
produce any other arrangement of the three variables.

qplot(var, value, data = df, fill = factor(row), geom="bar", stat
"identity", facets = ~ yoda)
qplot(row, value, data = df, fill = yoda, geom="bar", stat
"identity", facets = ~ var)
etc

Hadley

-- 
http://had.co.nz/