[R] Counting by rows based on multiple criteria

[jim holtman]

Will this do it for you:

> x <- matrix(sample(c(-1,0,1), 6000, TRUE), ncol=6)
> # compute the occurances
> gt0 <- rowSums(x > 0)
> lt0 <- rowSums(x < 0)
> eq0 <- rowSums(x == 0)
> x <- cbind(x, result=ifelse(eq0 == 6, -9999,
+     ifelse(gt0 > lt0, gt0,
+     ifelse(gt0 == lt0, 0, -lt0))))
> head(x,20)
                        result
 [1,]  1 -1  0 -1  0  0     -2
 [2,] -1  1  0  1 -1  1      3
 [3,] -1  0  1  1  1 -1      3
 [4,] -1  1  1  0 -1  0      0
 [5,]  1 -1 -1  0  1 -1     -3
 [6,]  1  0  1  0  0  0      2
 [7,]  1 -1  1  1  1 -1      4
 [8,]  1 -1  0  1 -1  1      3
 [9,]  0 -1  1 -1  0 -1     -3
[10,]  1  0 -1  0 -1  0     -2
[11,] -1  1  1  1  1 -1      4
[12,]  0  0  0  0  1  1      2
[13,]  0  0  1  1  0  0      2
[14,]  1  0  0 -1  0 -1     -2
[15,] -1  0  0  0  0  1      0
[16,]  1  0  0  0  1  0      2
[17,] -1 -1  1 -1  0  0     -3
[18,]  1  1  1  0  0 -1      3
[19,]  0  1 -1  1 -1  1      3
[20,]  1 -1 -1  0  1  0      0
>
>
>


On Mon, Feb 8, 2010 at 6:54 AM, Steve Murray <smurray444 at hotmail.com> wrote:
>
> Dear all,
>
> I have a data frame of 6 columns and ~60000 rows which I hope to perform the following calculation on.
>
> For each row, I wish to determine whether there are a greater number of positive or negative numbers. Then, if there are more positive numbers in the row, count how many occur - but if there are more negative numbers in the row, count them instead and insert a minus symbol before (e..g -4, to denote that this was determined on negative numbers).
>
> If the number of positive and negative numbers in a given row are equal, then return a zero for that row.
>
> Finally, if all values in a row are zero (i.e. neither positve or negative) then return -99999.
>
>
> I've had a go at this myself for some considerable time, trying the use of an 'apply' (by rows) function, but seem unable to successfully achieve the above.
>
> Any help would be very gratefully received.
>
> Many thanks,
>
> Steve
>
>
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-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?