[R] counting columns that match criteria

[Dennis Murphy]

Hi:

Here's a toy example:

# Default var names are V1-V20:
u <- as.data.frame(matrix(rpois(100, 3), ncol = 20))
u <- transform(u,
    ngt1 = apply(u[, c('V1', 'V4', 'V9', 'V15')], 1, function(x) sum(x > 1)) )
u

HTH,
Dennis

On Thu, Nov 10, 2011 at 7:24 AM, JL Villanueva <jlpostage at gmail.com> wrote:
> Hi,
>
> I am a little new in R but I'm finding it extremely useful :)
>
> Here's my tiny question:
>
> I've got a table with a lot of columns. What I am interested now is to
> evaluate how many of 4 columns have a value greater than 1.
> I think it can be done with subset() but it will take a very long condition
> and become unfeasible if I want to compare more than 4 columns.
>
> I put here a small example
>
> Col1  Col2  Col3  Col 4
> 1        1       1       1             <-0 columns greater than 1
> 2        1       1       1             <-1 column greater than 1
> 4        1       4      1              <-2 columns greater than 1
> 3        3       3       3             <-3 columns greater than 1
>
> Then I want to filter by that number, my idea is to create a new column
> storing the number calculated and subset() by it.
>
> Any hints?
> Thanks in advance
>
> JL
>
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>
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