[R] Rows index/colProds

[Henrik Bengtsson]

What is your sessionInfo()?

/Henrik

On Sun, Aug 15, 2010 at 10:47 AM, pablo.andrade <pablo.andrade at gmail.com> wrote:
>
> Hi,
>
> Is there any function to replace colProds that finds column-wise products of
> a matrix?
>
> Or is there any other function that would give a better solution this
> problem ?
>
> I have a matrix and an array, example:
>
>> a
>                     GSM1.CEL  GSM2.CEL  GSM1.CEL
> 10000_at               1             3             1
> 10001_at               3             3             3
>
>> b
> 10000_at 10001_at
>       1        3
>
> I want to find the number of occurrences of this array within the matrix
> (which in this case is 2).
>
>> a==b
> gives me:
>                     GSM1.CEL  GSM2.CEL  GSM1.CEL
> 10000_at          TRUE         FALSE          TRUE
> 10001_at          TRUE          TRUE          TRUE
>
> What I have done is :
>
>> colProds(a==b)
>                     GSM1.CEL  GSM2.CEL  GSM1.CEL
>                            1           0             1
>
>> sum(colProds(a==b))
> 2                    -----> that gives the value of 2 that I want.
>
> The problem is: if the matrix "a" is actually a vector (matrix 1xN), the
> function "colProds" multiply the elements of the row as if it was a column:
>
>> a
> 10000_at
>       1
>> b
>       GSM1.CEL  GSM2.CEL  GSM1.CEL
>            1             3             1
>> a==b
>
>       GSM1.CEL  GSM2.CEL  GSM1.CEL
>         TRUE         FALSE          TRUE
>
>> colProds(a==b)
> [1] 0
>
>
> I could use a if length(b==1) find sum(a==b) instead of sum(colProds(a==b)),
> but I would have to use this condition many time through the code, so I
> would like to know if there a better way to do that.
>
> Thank you very much.
> Pablo.
>
>
> --
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>
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