[R] simple question

[David Winsemius]

On Apr 22, 2010, at 1:36 PM, Zoppoli, Gabriele (NIH/NCI) [G] wrote:

> Hi
>
> how can I find, in a vector of characters, which is the most  
> frequent one?

 > a <- sample(letters[1:10], 100, replace=TRUE)
 > table(a)
a
  a  b  c  d  e  f  g  h  i  j
10  7  7 13  7 12  1 14 15 14
 > max(table(a))
[1] 15
 > which.max(table(a))
i
9   # so the ninth element in the table is the max
 > table(a)[which.max(table(a))]
  i
15   # but the table entry needs to be extracted if you want the count.

>
> Thanks
>
> Gabriele Zoppoli, MD
> Ph.D. Fellow, Experimental and Clinical Oncology and Hematology,  
> University of Genova, Genova, Italy
> Guest Researcher, LMP, NCI, NIH, Bethesda MD
>
> Work: 301-451-8575
> Mobile: 301-204-5642
> Email: zoppolig at mail.nih.gov
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David Winsemius, MD
West Hartford, CT