[R] barplot as histogram

Duncan Murdoch
Fri, 04 Nov 2011 18:19:10 -0000

On 04/11/2011 2:04 PM, Jesse Brown wrote:
> Hello:
>
> I'm dealing with an issue currently that I'm not sure the best way
to
> approach. I've got a very large (10G+) dataset that I'm trying to
create
> a histogram for. I don't seem to be able to use hist directly as I can
> not create an R vector of size greater than 2.2G. I considered
> condensing the data  previous to loading it into R  and just plotting
> the frequencies as a barplot; unfortunately, barplot does not support
> plotting the values according to a set of x-axis positions.
>
> What I have is something similar to:
>
> ys<- c(12,3,7,22,10)
> xs<- c(1,30,35,39,60)
>
> and I'd like the bars (ys) to appear at the positions described by xs.
I
> can get this to work on smaller sets by filling zero values in for
> missing ys for the entire range of xs but in my case this would again
> create a vector too large for R.
>
> Is there another way to use the two vectors to create a simulated
> frequency histogram? Is there a way to create a histogram object (as
> returned by hist) from the condensed data so that plot would handle it
> correctly?

Follow your own last suggestion.  Take a small subset of your data, and
calculate

x <- hist(data, plot=FALSE)

str(x) will show you the structure of the object in x.  Modify the
entries to reflect your full dataset, and then

plot(x)

will show it.

Duncan Murdoch