Create 4 percentage bar plot in same figure reseting to 0 the count in each one

Question

I have a data frame (dat2) with:

> summary(dat2)
     combs             label                   Groups    
 Min.   :    1.00   Length:21172       (0,1]      :1573  
 1st Qu.:    4.00   Class :character   (1,5]      :5777  
 Median :    9.00   Mode  :character   (5,12]     :5632  
 Mean   :   86.46                      (12,30]    :4061  
 3rd Qu.:   24.00                      (30,100]   :2976  
 Max.   :49280.00                      (100,5e+04]:1153 

I already gathered some code from stackoverflow in order to create a 4 facet plot bar showing percentages.

ggplot(dat2,aes(x=Groups)) + 
  stat_bin(aes(n=nrow(dat2), y=..count../n)) +
  scale_y_continuous(formatter = "percent") + 
  facet_wrap(~ label)

The thing is I want to reset the counter for each subplot, so each label group data will be calculated dividing by the total number of rows in that particular label and not by the total.

Answer 1

Calculate the number of observations per label and add it to your dataset

nLabel <- 4
nGroups <- 3
nObs <- 10000
dataset <- data.frame(label = factor(sample(nLabel, nObs, prob = runif(nLabel), replace = TRUE)))
library(plyr)
dataset <- ddply(dataset, .(label), function(x){
  data.frame(Groups = sample(nGroups, nrow(x), prob = runif(nGroups), replace = TRUE))
})
dataset$nLabel <- ave(dataset$Groups, by = dataset$label, FUN = length)
dataset$Groups <- factor(dataset$Groups)
library(ggplot2)
library(scales)
ggplot(dataset, aes(x = Groups)) + geom_histogram(aes(n = nLabel, y = ..count.. / n)) + facet_wrap(~label, scales = "free") + scale_y_continuous(label = percent)