[R] 2 x 3 Probability under the null

[(Ted Harding)]

On 27-Oct-11 04:09:46, Jim Silverton wrote:
> I have a 2 x 3 matrix called snp and I want to compute the following
> probability:
> 
> choose(sum(snp[,1]), snp[1,1]) * choose(sum(snp[,2]), snp[1,2]) *
> choose(sum(snp[,3]), snp[1,3])/choose(sum(snp), sum(snp[1,]))
> 
> but I keep getting Infs and NaNs. Is there a function that can do this
> in R?
> -- 
> Thanks,
> Jim.

Since 1/0 --> Inf, and 0/0 --> NaN, it seems likely that your
data lead to zero denominators. However, true diagnosis needs
to see what your data really are. What is a typical 2x3 matrix
that gives such results?

If this guess is correct, then no possible function in R can
resolve the problem! For data where the problem does not arise,
then you can of course write your own function to implement
your code above for an arbitrary 2x3 matrix.

Hoping this helps,
Ted.

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Date: 27-Oct-11                                       Time: 07:32:30
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