R help - May 2010 - Comparing multiple columns in matrix

We're running Monte Carlo repeated measures for several groups.

The goal is to determine the number of time each group has the highest
score.

A toy example:

  [,1] [,2] [,3]
   0.1  0.2  0.3
   0.1  0.2  0.3
   0.1  0.2  0.3
   0.1  0.3  0.2
   0.1  0.3  0.2
   0.2  0.3  0.1

For this example:  group 1 was the top 0 times, group 2 was the top 3
times., group 3 was the top 3 times

I can do this with some messy & statements or loops, but am looking for
an easier way.

Any suggestion?

-N

Hi:

Here's one approach. Let x be your matrix; then
table(apply(x, 1, which.max))

2 3
3 3

If you prefer the result in data frame form, then
> as.data.frame(table(apply(x, 1, which.max)))
  Var1 Freq
1    2    3
2    3    3

HTH,
Dennis

On Mon, May 31, 2010 at 2:39 AM, Noah Silverman
<noah@smartmediacorp.com>wrote:
> We're running Monte Carlo repeated measures for several groups.
>
> The goal is to determine the number of time each group has the highest
> score.
>
> A toy example:
>
>  [,1] [,2] [,3]
>   0.1  0.2  0.3
>   0.1  0.2  0.3
>   0.1  0.2  0.3
>   0.1  0.3  0.2
>   0.1  0.3  0.2
>   0.2  0.3  0.1
>
> For this example:  group 1 was the top 0 times, group 2 was the top 3
> times., group 3 was the top 3 times
>
> I can do this with some messy & statements or loops, but am looking for
> an easier way.
>
> Any suggestion?
>
> -N
>
> ______________________________________________
> R-help@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>
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