[R] ylim problem in barplot

[Ben Bolker]

Bliese, Paul D LTC USAMH <paul.bliese <at> us.army.mil> writes:

> 
> R Version 2.2.0
> 
> Platform:  Windows
> 
> When I use barplot but select a ylim value greater than zero, the graph
> is distorted.  The bars extend below the bottom of the graph.
>

  The problem is that barplot() is really designed to work
with zero-based data.  I don't know if the Powers That Be
will say that "fixing" this would violate the spirit of
barplot (although I see there is some code in barplot 
that deals with figuring out the base of the rectangle
in the logarithmic case, where 0 obviously doesn't work)

 Here's a workaround:

barplot(c(200,300,250,350)-150,axes=FALSE)
axis(side=2,at=seq(0,200,by=50),labels=seq(150,350,by=50))

 And here's a diff: if you want to hack barplot yourself,

sink("newbarplot.R")
barplot.default
sink()
## go edit newbarplot.R; add barplot.default <- to
## the first line, remove the namespace information
## from the last line, and substitute the lines
## in the first chunk below with exclamation points for 
## the lines in the second chunk below with exclamation
## points
source("newbarplot.R")

  cheers
    Ben

*** newbarplot2.R       2006-01-05 08:52:11.000000000 -0500
--- /usr/local/src/R/R-2.2.1/src/library/graphics/R/barplot.R   2005-10-06
06:22:59.000000000 -0400
***************
*** 85,97 ****
            if      (logy && !horiz && !is.null(ylim))  ylim[1]
            else if (logx && horiz  && !is.null(xlim))  xlim[1]
            else 0.9 * min(height)
!     } else {
!       rectbase <- if (!horiz && !is.null(ylim))
!         ylim[1]
!       else if (horiz && !is.null(xlim))
!         xlim[1]
!       else 0
!     }
      ## if stacked bar, set up base/cumsum levels, adjusting for log scale
      if (!beside)
        height <- rbind(rectbase, apply(height, 2, cumsum))
--- 85,92 ----
            if      (logy && !horiz && !is.null(ylim))  ylim[1]
            else if (logx && horiz  && !is.null(xlim))  xlim[1]
            else 0.9 * min(height)
!     } else rectbase <- 0
!
      ## if stacked bar, set up base/cumsum levels, adjusting for log scale
      if (!beside)
        height <- rbind(rectbase, apply(height, 2, cumsum))