On 20 Sep 2008, at 23:41, Ling, Gary (Electronic Trading) wrote:
Hi R users,
What is the fastest way to replace a(some) value(s) in a (numeric)
vector?
I checked ?replace, but its output is another vector.
1) I wonder if there's any function to perform in-place replacement?
How about
L[n] <- 0
which also works with index/value vectors:
L[c(0,n)] <- c(1,0)
2) Or any other function would do what I'm looking for with faster
speed?
> system.time(replicate(500, L <- replace(L,n,0)))
user system elapsed
1.027 1.179 2.203
> system.time(replicate(500, L[n] <- 0))
user system elapsed
0.508 0.552 1.054
I suppose that's the fastest you can get because of R's copy-on-write
semantics (if I understand the R internals correctly, it's always a
bit magical to me ...)
Best regards,
Stefan Evert
[ [EMAIL PROTECTED] | http://purl.org/stefan.evert ]
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