[R] Width of bars in barplot2

Marc Schwartz (via MN) mschwartz at mn.rr.com
Wed Mar 1 18:18:16 CET 2006

On Wed, 2006-03-01 at 12:01 -0500, Jamieson Cobleigh wrote:
> I'm using barplot2 to plot some data.  Is there any way to determine
> the width of the bars in the generated plot?  I know that barplot2
> returns a list of the coordinates of the center of each bar, but since
> there is some white space between each bar, I don't know how to get
> the width of each bar.
> Jamie

Unless you have modified the 'width' argument, the default width is 1.

Thus the sides of the bars are the centers +/- 0.5.

If you modified the width argument, then the widths are set to the
vector assigned.

This behavior is the same in barplot() and barplot2() by design.

As an example:

 # Draw a barplot. adjust the y axis to make some room
 # above the bars
 mp <- barplot2(1:10, ylim = c(0, 12))

 # Draw lines showing the bar width limits
 arrows(mp - 0.5, 2:11, mp + 0.5, 2:11, angle = 90, code = 3)


Marc Schwartz

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