Question

I have the following data.frame:

sample <- data.frame(day=c(1,2,5,10,12,12,14))
sample.table <- as.data.frame(table(sample$day))

Now what I’d like to do is graph the day against the count of days, so something like:

require(ggplot2)
qplot(Var1, Freq, data=sample.table)

I realized though that Var1 really really really wants to be a factor. This works fine for a small number of days, but is terrible when days becomes much larger because the graph becomes unreadable. If I change it to a numeric or integer, then instead of plotting day on the x-axis, it plots the count of day, e.g. 1,2,3,4,5,6,7.

What can I do so that if I have, say 5000 days, it is still visible well?

Answer 1

This is because when you use table you get a vector with names (which are characters), and when you convert to data.frame these get converted to factors with the default settings.

You could avoid this by using your original data and getting ggplot2 to count the data:

qplot(day, ..count.., data=sample, stat="bin", binwidth=1)

or just use a histogram,

qplot(day, data=sample, geom="histogram", binwidth=1)

Note that you can adjust the binwidth argument to count in larger groups.