R help - Jun 2006 - weird application of apply again

uugh : i promise that this will be my last question of the day.
i hate to constantly bother this group but it takes me time to get familar with
all of these functions, tricks and and manipulations.
i appreciate everyone's patience. i used too splus a lot
but i've gotten rusty.

i have a matrix of say 200 rows and 600 columns.

i have a function "getprofit" that takes two series and returns a
number.

getprofit<-function(series1, series2) {
do some stufff 
return(somenumber)

is there a way to do something clever so that
i call the function, getprofit, on the first two columns 
of the matrix ( where the first column is series1 and the second column is
series2 ), then the next two columns of the matrix,
then the next two columns of the matrix and so on and so forth return a 300 by 1
( oir 1 by 300, it doesn't matter ) vector of "somenumbers".

i ( maybe stupidly ) put the data in a matrix but
now i am thinking that wasn't a good thing to do ?
i can change it to some thing else if i have to.

                                thanks

Here is an example of adding up 2 consecutive rows, iterating through all
the row:
> x <- matrix(1:100,10)
> x
      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
 [1,]    1   11   21   31   41   51   61   71   81    91
 [2,]    2   12   22   32   42   52   62   72   82    92
 [3,]    3   13   23   33   43   53   63   73   83    93
 [4,]    4   14   24   34   44   54   64   74   84    94
 [5,]    5   15   25   35   45   55   65   75   85    95
 [6,]    6   16   26   36   46   56   66   76   86    96
 [7,]    7   17   27   37   47   57   67   77   87    97
 [8,]    8   18   28   38   48   58   68   78   88    98
 [9,]    9   19   29   39   49   59   69   79   89    99
[10,]   10   20   30   40   50   60   70   80   90   100
> sapply(seq(nrow(x)/2), function(z) sum(x[2*z-1,], x[2*z,]))
[1]  930  970 1010 1050 1090
>


On 6/20/06, markleeds@verizon.net <markleeds@verizon.net>
wrote:
>
>
> uugh : i promise that this will be my last question of the day.
> i hate to constantly bother this group but it takes me time to get familar
> with all of these functions, tricks and and manipulations.
> i appreciate everyone's patience. i used too splus a lot
> but i've gotten rusty.
>
> i have a matrix of say 200 rows and 600 columns.
>
> i have a function "getprofit" that takes two series and returns a
number.
>
> getprofit<-function(series1, series2) {
> do some stufff
> return(somenumber)
>
> is there a way to do something clever so that
> i call the function, getprofit, on the first two columns
> of the matrix ( where the first column is series1 and the second column is
> series2 ), then the next two columns of the matrix,
> then the next two columns of the matrix and so on and so forth return a
> 300 by 1 ( oir 1 by 300, it doesn't matter ) vector of
"somenumbers".
>
> i ( maybe stupidly ) put the data in a matrix but
> now i am thinking that wasn't a good thing to do ?
> i can change it to some thing else if i have to.
>
>                                thanks
>
> ______________________________________________
> R-help@stat.math.ethz.ch mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide!
> http://www.R-project.org/posting-guide.html
>


-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390 (Cell)
+1 513 247 0281 (Home)

What is the problem you are trying to solve?

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