R-devel,
The performance of as.Date differs by a large degree between one of my
machines with glibc 2.3.2:
> system.time(x <- as.Date(rep("01-01-2005", 100000), format = "%m-%d-%Y"))
[1] 1.17 0.00 1.18 0.00 0.00
and a comparable machine with glibc 2.3.3:
> system.time(x <- as.Date(rep("01-01-2005", 100000), format = "%m-%d-%Y"))
[1] 31.20 46.89 81.01 0.00 0.00
both with the same R version:
> R.version
_
platform i686-pc-linux-gnu
arch i686
os linux-gnu
system i686, linux-gnu
status
major 2
minor 1.0
year 2005
month 04
day 18
language R
I'm focusing on differences in glibc versions because of as.Date's use
of strptime.
Does it seem likely that the cause of this discrepancy is in fact
glibc? If so, can anyone tell me how to make the performance of the
second machine more like the first?
I have verified that using the chron package, which I don't believe
uses strptime, for the above character conversion performs equally
well on both machines.
Thanks in advance,
Jeff
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