R help - Jan 2008 - Barplot w/ single stacked bar

Hi All,

I can get the barplot function to do many types of plots, stacked or
otherwise. However, I cannot get it to do a *single* stacked bar. I've
searched several books & listserv archives to no avail. I suspect I'm
missing the obvious from the help file!

I can reach my goal in ggplot2, although the relative heights of the
bar's pieces don't seem quite right (it does generate a warning):

library(ggplot2)
x<-factor(1)
y<-factor( c("Male","Male","Female") )
mydata <- data.frame(x,y)
rm(x,y)
mydata

#These are close to my goal:
qplot( x, y, fill=y, geom="bar", data=mydata)

# or
ggplot(mydata, aes(x=x, y=y, fill=y)) + geom_bar()

# But this places the bars beside each other rather than stack them.
barplot( table(mydata$y), beside=FALSE)

Thanks!
Bob

========================================================Bob Muenchen (pronounced
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Statistical Consulting Center
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=========================================================

Muenchen, Robert A (Bob) wrote:
> Hi All,
> 
> I can get the barplot function to do many types of plots, stacked or
> otherwise. However, I cannot get it to do a *single* stacked bar. I've
> searched several books & listserv archives to no avail. I suspect
I'm
> missing the obvious from the help file!
> 
> I can reach my goal in ggplot2, although the relative heights of the
> bar's pieces don't seem quite right (it does generate a warning):
> 
> library(ggplot2)
> x<-factor(1)
> y<-factor( c("Male","Male","Female") )
> mydata <- data.frame(x,y)
> rm(x,y)
> mydata
> 
> #These are close to my goal:
> qplot( x, y, fill=y, geom="bar", data=mydata)
> 
> # or
> ggplot(mydata, aes(x=x, y=y, fill=y)) + geom_bar()
> 
> # But this places the bars beside each other rather than stack them.
> barplot( table(mydata$y), beside=FALSE)
> 
> Thanks!
> Bob
Bob,

Try this:

  barplot(as.matrix(table(mydata$y)), beside = FALSE)

Conceptually, for a stacked bar, each bar is a column in a matrix. The
components in a stacked bar are the row values in the column.

Thus, you need to create a single column matrix from your table.

One might question the value of such a plot however, if the intent is to
provide a visual representation of the difference in counts/proportions
between two groups. A side-by-side barplot or a dotchart would seem to
be better here.

HTH,

Marc Schwartz

> I can reach my goal in ggplot2, although the relative heights of the
> bar's pieces don't seem quite right (it does generate a warning):
>
> library(ggplot2)
> x<-factor(1)
> y<-factor( c("Male","Male","Female") )
> mydata <- data.frame(x,y)
> rm(x,y)
> mydata
Ooops!  There was a bug in stat_bin that occurred when there was a
single categorical x value.  It'll be fixed in the next version.

Hadley


-- 
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