[R] [solved] How to count numbers of a vector and use them as index values?

[Paul Menzel]

Dear Sarah,


Am Sonntag, den 31.07.2011, 18:10 -0400 schrieb Sarah Goslee:

> I would use something like this:
> 
> > x <- c(2,2,3,3,4,6)
> > table(x)
> x
> 2 3 4 6
> 2 2 1 1
> > x <- factor(x, levels=1:8)
> > table(x)
> x
> 1 2 3 4 5 6 7 8
> 0 2 2 1 0 1 0 0

awesome. Thank you.

Looking further I found the article »Thinking in R: vectors« on
R-bloggers [1]. The given example there returned a list though by using
`lapply()` and the author is asking at the end: »Any R experts out there
with suggestions for a non-lapply solution?«. So Derek-Jones, Sarah just
gave you the answer.

A further note regarding the example in [1], instead of

	length(X[X == n])

to count the number of occurrences you can also use `sum(X == n)`
relying on the fact that `TRUE` and `FALSE` are converted to the
integers `1` and `0`.


Thanks,

Paul


[1] http://www.r-bloggers.com/thinking-in-r-vectors/
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