R - histogram within histogram

Question

I am trying to generate a histogram from below data

a   11
a   14
a   23
b   12
b   21
c   17
c   14
c   29
c   22
c   25

This is my target plot

Looks like i can do something like this with ggplot but i dont have ggplot in my system. Is it possible to generate it without ggplot?

Answer 1

Update

Here's a better version of the code which can be more easily adjusted to any number ranges to separate by:

dat <- data.frame(c1 = c("a", "a", "a", "b", "b", rep("c", 5)), c2=c(11, 14, 23, 12, 21, 17, 14, 29, 22, 25))

groups <- levels(dat$c1)
nranges <- 2
limits <- c(10, 20, 30) #Must have length equal to nranges + 1
intervals <- sapply(1:nranges, function(i) paste0(limits[i], "-", limits[i+1]))

frequencies <- sapply(1:nranges, function(i) sapply(groups, function(j) sum(dat[dat$c2>limits[i] & dat$c2<limits[i+1],1]==j)))
# Or using table(). One of them might be faster than the other for large data
#frequencies <- sapply(1:nranges, function(i) rowSums(table(dat[dat$c2>limits[i] & dat$c2<limits[i+1],])))

barplot(frequencies, beside = TRUE, col=1:length(groups), names.arg=intervals)

The result is the same as below with different colors and appropriate labels for the groups:

Original

This might not be ideal for your real data, but it works for your sample and will give you a start:

dat <- data.frame(c1 = c("a", "a", "a", "b", "b", rep("c", 5)), c2=c(11, 14, 23, 12, 21, 17, 14, 29, 22, 25))

groups <- levels(dat$c1)
dat1 <- sapply(groups, function(i) sum(dat[dat$c2>10 & dat$c2<20,1]==i))
dat2 <- sapply(groups, function(i) sum(dat[dat$c2>20 & dat$c2<30,1]==i))

barplot(matrix(c(dat1, dat2), ncol=2), beside = TRUE, col=c("Red", "Green", "Blue"))

Which generates:

The idea is to calculate the frequencies and then plot those using barplot with stacked data side by side, instead of trying to use hist().