How to align or center the bars of a histogram on the x axis?

Question

qplot(carat,data=diamonds,geom="histogram",binwidth=1,xlim=c(0,3))

I use this code to draw a histogram. But the result is different from that of book.

Answer 1

There are two possibilities, either use the center parameter as suggested by Richard Telford or the boundary parameter.

Both codes below will create the same chart:

library(ggplot2)  # CRAN version 2.2.1 used
qplot(carat, data=diamonds, geom = "histogram", binwidth = 1, xlim = c(0,3),
      center = 0.5)
qplot(carat, data=diamonds, geom = "histogram", binwidth = 1, xlim = c(0,3),
      boundary = 0)

For more details, please, see ?geom_histogram.