Thank you Jens. I will try your solutions and post the solutions/problems I
have.
Cheers
Peter

2010/1/7 Jens Oehlschlägel <oehl_list@gmx.de>

> Peter,
>
> ff objects are not allowed as subscripts to ff objects. You can take
> several routes
>
> 1) use bit objects instead of logical or ff logical. This is fast and takes
> factor 32 less RAM than logicals (BTW bit objects can be coerced to ff via
> as.ff() and as.bit() but they convert to vmode "boolean" (1 bit), not
> "logical" (2 bits). Examples for working with bit are on
> http://ff.r-forge.r-project.org/ff&bit_UseR!2009.pdf
>
> 2) convert your logicals into positive integer subscripts (assuming that
> there are not too many elements selected, as you assume if writing
> bigData[select,]
>
> 3) keep your logical in a ff logical or ff boolean and then do chunked
> looping over both - the ff with the subscripts and the ffdf - and in each
> chunk convert the logical selection to integers, see 2)
>
> HTH
>
>
> Jens Oehlschlägel
>
>
> P.S. you  might want to try the newer version on r-forge. It has several
> improvements but is not yet on CRAN because there is currently some issue
> with snow leopard.
>
>

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