Multiple histograms in ggplot2

Question

Here is a short part of my data:

dat <-structure(list(sex = structure(c(1L, 1L, 1L, 1L, 1L, 1L, 1L, 
1L, 1L, 1L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L, 2L),          


        

Answer 1

To follow up on chl's example - here's how to duplicate your base graphic with ggplot. I would heed his advice in looking to dotplots as well:

library(ggplot2)
dat.m <- melt(dat, "sex") 

ggplot(dat.m, aes(value)) + 
  geom_bar(binwidth = 0.5) + 
  facet_grid(variable ~ sex)

Answer 2

You can try grid.arrange() from the gridExtra package; i.e., store your plots in a list (say qplt), and use

do.call(grid.arrange, qplt)

Other ideas: use facetting within ggplot2 (sex*variable), by considering a data.frame (use melt).

As a sidenote, it would be better to use stacked barchart or Cleveland's dotplot for displaying items response frequencies, IMO. (I gave some ideas on CrossValidated.)

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For the sake of completeness, here are some implementation ideas:

# simple barchart
ggplot(melt(dat), aes(x=as.factor(value), fill=as.factor(value))) + 
  geom_bar() + facet_grid (variable ~ sex) + xlab("") + coord_flip() + 
  scale_fill_discrete("Response")

my.df <- ddply(melt(dat), c("sex","variable"), summarize, 
               count=table(value))
my.df$resp <- gl(3, 1, length=nrow(my.df), labels=0:2)

# stacked barchart
ggplot(my.df, aes(x=variable, y=count, fill=resp)) + 
  geom_bar() + facet_wrap(~sex) + coord_flip()

# dotplot
ggplot(my.df, aes(x=count, y=resp, colour=sex)) + geom_point() + 
  facet_wrap(~ variable)