[R] stacked barplot with positive and negatvie values

[Marc Schwartz]

On Tue, 2007-05-15 at 17:54 +0200, Paul Magdon wrote:
> Hello I'm trying to create a barplot with a couple of stacked positive 
> values and with one negative value for each group.
> 
> example:
> 
> trees<-c(20,30,10)
> shrubs<-c(12,23,9)
> veg<-c(2,3,4)
> soil<-c(-100,-123,-89)
> example1<-t(cbind(trees,shrubs,veg))
> 
> barplot(example1)
> 
> #this works so far
> 
> #but now:
> 
> example2<-t(cbind(trees,shrubs,veg,soil))
> barplot(example2)
> 
> This shows no more stacked bars. But I want to keep the bars like 
> example1 and just add the negative values which have another scale 
> downwards.
> So I tried:
> 
> barplot(example1,axes=F)
> barplot(example2["soil",],add=T,axes=F)
> axis(side=2,at=c(-150,-100,-50,0,10,20,30))
> 
> But I still does not work for the axis??
> 
> I would appriciate any kind of hint
> Greetings
> Paul Magdon


How about this:

  # Set up a 2 x 1 plot
  # See ?par
  par(mfrow = c(2, 1)) 

  #adjust the axis side 1 margin to 0
  # See ?par
  par(mar = c(0, 4, 4, 2))

  # Do the plot of the positive values
  # define the y limits and set the y axis type to 'i'
  # See ?par for 'xaxs' and 'yaxs'
  barplot(example2[-4, ], yaxs = "i", ylim = c(0, 60), las = 2)

  # Set the axis side 4 margin to 0
  # so that there is no gap
  par(mar = c(5, 4, 0, 2))

  # Now do the negative values, using the same logic
  barplot(example2[4, ], yaxs = "i", ylim = c(-125, 0), las = 2)


HTH,

Marc Schwartz