ggplot geom_boxplot with box fill and correctly spaced x-axis scale

boxplot_attempt1.r

library(ggplot2)
ggplot(data.df, aes(x=factor(time), y=value)) +
    geom_boxplot(aes(fill=measure)) +
    xlab("Time (time units)") + ylab("Value (value units)") +
    scale_fill_discrete(name = "Measure")

boxplot_attempt2.r

ggplot(data.df, aes(x=time, y=value)) +
    geom_boxplot(aes(fill=measure)) +
    xlab("Time (time units)") + ylab("Value (value units)") +
    scale_fill_discrete(name = "Measure")

boxplot_attempt3.r

ggplot(data.df, aes(x=time, y=value)) +
    geom_boxplot(aes(fill=measure, group=factor(time))) +
    xlab("Time (time units)") + ylab("Value (value units)") + 
    scale_fill_discrete(name = "Measure")

boxplot_correct1.r

ggplot(data.df, aes(y=value, x=time)) +
    geom_boxplot(aes(position = factor(time), fill=measure)) +
    xlab("Time (time units)") + ylab("Value (value units)") +
    scale_fill_discrete(name = "Measure")

boxplot_correct2.r

ggplot(data.df, aes(y=value, x=time)) +
    geom_boxplot(aes(position = factor(time), fill=measure)) +
    scale_x_continuous(breaks = unique(data.df$time)) +
    xlab("Time (time units)") + ylab("Value (value units)") +
    scale_fill_discrete(name = "Measure")

sim_boxplot_data.r

data.df = data.frame(time = rep(c(0,3,6,12,24,48),each=50),
    value = rnorm(300, 20, 5),
    measure = factor(rep(rep(c("A","B"),each=25), 6)))