To "unjam" the plot, use xlim
:
qplot(x) + geom_histogram(binwidth = 0.2, aes(fill = ..count..), colour='black', fill='skyblue') + xlim(0,1)
I'm not sure why you want to use variation in color here when column height is already giving you that information. That's the whole point of a histogram, and then you don't have to worry about confusing color-blind people. So why not just:
qplot(x) + geom_histogram(binwidth = 0.2, colour='black', fill='skyblue') + xlim(0,1)
Here's the toy data I used to test it:
x <- c(0.41, 0.42, 0.47, 0.47, 0.49, 0.50, 0.51, 0.55, 0.56, 0.57, 0.59, 0.61, 0.62, 0.65, 0.68, 0.69, 0.70, 0.75, 0.78, 0.79)
And here's a .png of the plot I got:
与恶龙缠斗过久,自身亦成为恶龙;凝视深渊过久,深渊将回以凝视…