[R] Row-wise two sample T-test on subsets of a matrix

[Ranjan Maitra]

Here's one suggestion: convert the matrix into a three-dimensional array and use apply on it. 

Ranjan

On Thu,  1 Mar 2007 11:51:29 -0600 (CST) Nameeta Lobo <nlobo at uchicago.edu> wrote:

> Hello all,
> 
> I am trying to run a two sample t-test on a matrix which is a
> 196002*22 matrix. I want to run the t-test, row-wise, with the
> first 11 columns being a part of the first group and columns
> 12-22 being a part of the second group. 
> 
> I tried running something like (temp.matrix being my 196002*22
> matrix)
> 
> t.test(temp.matrix[,1:11],temp.matrix[,12:22],paired=TRUE)
> 
> or somthing like
> 
> as.numeric(t.test(temp.matrix[,1:11],temp.matrix[,12:22],paired=TRUE)[[1]])
> so as to only capture the t-value alone and 
> 
> and I get a result for the whole matrix instead of a row-wise
> result. 
> 
> I want to avoid using a "for" loop to increment the number of
> rows as it would take a huge amount of time.
> 
> 
> Any suggestions would be really appreciated.
> 
> thanks
> nameeta
> 
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