On 12/22/2008 1:55 PM, murdoch at stats.uwo.ca wrote:> I was wondering if copies were made when a component of a complex nested
> list structure was extracted but not modified. I was happy that the
> answer was no, but was surprised that copies weren't made even if the
> extracted bit was modified:
>
> > x <- list(a=list(b=numeric(1000000)))
> > y <- x[[c(1,1)]]
> > y[1] <- 3.14159
> > x[[c(1,1)]][1]
> [1] 3.14159
>
> Unfortunately, this exists in today's release of 2.8.1. I should have
> done this test last week!
The fix looks easy: The problem is that the NAMED status of the
component being extracted was miscalculated when using a vector index.
I'll commit a change after testing...
Duncan Murdoch
>
> Duncan Murdoch
>
> > sessionInfo()
> R version 2.8.1 (2008-12-22)
> i386-pc-mingw32
>
> locale:
> LC_COLLATE=English_United States.1252;LC_CTYPE=English_United
> States.1252;LC_MONETARY=English_United
> States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252
>
> attached base packages:
> [1] stats graphics grDevices utils datasets methods base
>
> loaded via a namespace (and not attached):
> [1] tools_2.8.1
>
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