Dodging preserves the vertical position of an geom while adjusting the horizontal position.
position_dodge(width = NULL, preserve = c("total", "single"))
Dodging width, when different to the width of the individual elements. This is useful when you want to align narrow geoms with wider geoms. See the examples.
Should dodging preserve the total width of all elements at a position, or the width of a single element?
# By default, dodging preserves the total width. You can choose # to preserve the width of each element: ggplot(mtcars, aes(factor(cyl), fill = factor(vs))) + geom_bar(position = position_dodge(preserve = "single"))#># see ?geom_boxplot and ?geom_bar for more examples # In this case a frequency polygon is probably a better choice ggplot(diamonds, aes(price, colour = cut)) + geom_freqpoly()#># Dodging with various widths ------------------------------------- # To dodge items with different widths, you need to be explicit df <- data.frame(x = c("a","a","b","b"), y = 2:5, g = rep(1:2, 2)) p <- ggplot(df, aes(x, y, group = g)) + geom_col(position = "dodge", fill = "grey50", colour = "black") p# A line range has no width: p + geom_linerange(aes(ymin = y - 1, ymax = y + 1), position = "dodge")#> Warning: Width not defined. Set with `position_dodge(width = ?)`# So you must explicitly specify the width p + geom_linerange( aes(ymin = y - 1, ymax = y + 1), position = position_dodge(width = 0.9) )# The same principle applies to error bars, which are usually # narrower than the bars p + geom_errorbar( aes(ymin = y - 1, ymax = y + 1), width = 0.2, position = "dodge" )