[R] Combining 2 arrays into a third array via a function

[David Winsemius]

Better to not use c as a variable name. It's such a useful function  
name.

This is what I would have tried:

col3 <- expand.grid(item=params.data$item, examinee=examinees.data 
$examinee)
col3$p_val <- p( c( params.data[ col3["item"],     c("a1", "a2", "b1",  
"b2", "c") ],
                 examinees.data[ col3["examinee"], c("theta1",  
"theta2")]
                   )
               )

If you had provided executable test data I would have tested it, but I  
am getting rather bored with creating such for posters who won't  
follow the posting guide. If you had just used dput() around those  
calls to head() it would have been trivial. As it is, I am not sure if  
this will properly run. Could need a different "driving" construction  
to get the values of col3 to "feed through" to the row indices. Or  
have any number of stoopid errors.

-- 
David Winsemius

On Mar 1, 2009, at 11:47 AM, Kevski wrote:

>
> I'm completely stumped and seem to be going around for 2 days in the  
> wrong
> circles. Here's what I have in 2 dataframes:
>
>> dim(params.data); head(params.data, n=2)
> [1] 284   6
> item        a1        a2   b1   b2   c
> 1    1 0.6671587 0.9588642 -3.5  -3.437961 0.2
> 2    2 1.1296298 1.4899307 -3.5  -4.146118 0.2
>
>> dim(examinees.data); head(examinees.data, n=2)
> [1] 1600    3
> examinee theta1 theta2
> 1        1     -3   -3.133437
> 2        2     -3   -3.293341
>
> I also have a function, p(), that takes on values for a1, a2, b1,  
> b2, c,
> theta1, and theta2, then outputs a value.
>
> I would like to produce a 3-column array that is 284*1600 = 454400  
> rows long
> for my simulator. Somthing like:
> examinee    item  p
> 1            1      1   p-value
> 2            1      2   p-value
> ...
> 454399 1600 283   p-value
> 454400 1600 284   p-value
>
> My brain seems to be stuck in a for-loop loop. I'm sure there is an  
> elegant
> and efficient R way to do this, but I can't seem to find the right  
> brain
> prompts in help pages, forum searches, or my trusty R Book. So, I  
> appreciate
> any guidance you might be able to provide.
>
> Cheers,
> Kev-
> -- 
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>
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