Question

I’ve been working with R language, I’ve created a histogram from a data file this way:

a <- read.table("_datafile.txt");

b <- table(a);

c <- as.numeric(names(b));

hist(c, 100);

This is the result, in the attached image:

Histogram http://www.imagehost.it/dm/FILK/istogrammaBis.png

My problem is that I’d like to exclude the 1rst bar of the histogram.

D’you know the R command to do it?

Thanx

Answer 1

hist uses ‘Sturges’ breaks (equal spaced intervals of number determined by nclass.Sturges) as the default break locations, but you are over-riding that. The second break value would be

seq( min(x), max(x), by= diff(range(x))/10 )[2]

So:

hist(c[ c >= seq( min(c), max(c), by= diff(range(c))/10 )[2], 9 ] )

I reduced the number of bins to keep the categories the same. If you want to see the formula for the number of breaks in the default just type:

nclass.Sturges

It’s not uncommon to find people puzzled by the behavior of hist with small numbers of equally spaced observations. because the result looks irregular. Try:

hist(0:8)