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277

answers:

2

I am starting to use ggplot2. I have some small n (about 30 or so) granular data with lots of overlap. Neither jitter nor alpha (transparency) are suitable. Instead a stripchart with stack and offset do it best but I do not know how to do it in ggplot2. Do you know?

To see what the end result should be click on this graphic.

Here is the script I used a few years ago.

stripchart(SystData$DayTo1Syst~SystData$strain,vertical=TRUE,method="stack",pch=19,offset=.3,xlab="Strain",main="Rapidity of Systemic Disease Onset",ylab="Days post inoculation")
+3  A: 
# your data
df <- data.frame(gp = rep(LETTERS[1:5], each =8), y = sample(1:4,40,replace=TRUE))
# calculate offsets
df <- ddply(df, .(y, gp), transform, offset = (1:length(gp)-1)/20)
qplot(gp, y, data=df) + stat_identity(aes(as.numeric(gp)+offset)) + theme_bw() 
xiechao
+4  A: 

You can use position_dodge.

df <- data.frame(gp = rep(LETTERS[1:5], each =8), 
                 y = sample(1:4,40,replace=TRUE))
qplot(gp,y,data=df,order=y,position=position_dodge(width=0.5))

alt text

Jyotirmoy Bhattacharya
If you look closely, this is not what Farrel wants: position dodge spread all points, while the example figure only spreads overplotted points
xiechao