Hi,
Please consider the following code:
a <- seq.int(10) # create a
tracemem(a)
a[1:4] <- 4:1 # no internal copy
b <- a # no internal copy
b[1:4] <- 1:4 # copy, b is not a any more
a[1:4] <- 1:4 # copy, but why?
With results:
> a <- seq.int(10)
> tracemem(a)
[1] "<0x1792bc0>"
> a[1:4] <- 4:1
> b <- a
> b[1:4] <- 1:4
tracemem[0x1792bc0 -> 0x1792b58]:
> a[1:4] <- 1:4
tracemem[0x1792bc0 -> 0x1792af0]:
##
Could you provide a brief explanation or point me to a source why R
needs a copy in the final step?
Best,
Denes
> sessionInfo()
R version 3.1.0 (2014-04-10)
Platform: x86_64-pc-linux-gnu (64-bit)
locale:
[1] LC_CTYPE=en_US.UTF-8 LC_NUMERIC=C
[3] LC_TIME=en_US.UTF-8 LC_COLLATE=en_US.UTF-8
[5] LC_MONETARY=en_US.UTF-8 LC_MESSAGES=en_US.UTF-8
[7] LC_PAPER=en_US.UTF-8 LC_NAME=C
[9] LC_ADDRESS=C LC_TELEPHONE=C
[11] LC_MEASUREMENT=en_US.UTF-8 LC_IDENTIFICATION=C
attached base packages:
[1] stats graphics grDevices utils datasets methods base
______________________________________________
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel
