Three plots to show that geom_jitter() calls must pass a position=position_jitter() argument to preserve jittering width

geomJitterVersusJitter.R

library(ggplot2)
set.seed(1001)

x <- rep(0, times = 1000)
x.jittered <- jitter(x, amount = 2)
y <- rnorm(1000)

dd <- data.frame(x, x.jittered, y)

p1 <- ggplot()
set.seed(1001)
p1 <- p1 + geom_jitter(
                     aes(x    = x,
                         y    = y
                     ), data  = dd,
                        width = 2
           )
p1 <- p1 + opts(title = "Plot using geom_jitter() and width=2")
print(p1)

p2 <- ggplot()
p2 <- p2 + geom_point(
                     aes(x    = x.jittered,
                         y    = y
                     ), data  = dd
           )
p2 <- p2 + opts(title = "Plot using geom_point() and jitter(x, amount=2)")
print(p2)

# To prove that x.jittered values lie outside the plotting window defined in p1
head(dd)
str(p1)

# Proof that the position_jitter call must be explicit
p3 <- ggplot()
set.seed(1001)
p3 <- p3 + geom_jitter(
                     aes(x    = x,
                         y    = y
                     ), data  = dd,
                        position = position_jitter(width = 2)
           )
p3 <- p3 + opts(title = "Plot using geom_jitter() and explicit position_jitter call")
print(p3)