R help - Feb 2010 - Counting by rows based on multiple criteria

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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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
>
>
> _________________________________________________________________
> Do you have a story that started on Hotmail? Tell us now
>
> ______________________________________________
> R-help at 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.
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem that you are trying to solve?

Spot on, thanks very much indeed.

Steve

 		 	   		  
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