[Rd] R's IO speed
maechler at stat.math.ethz.ch
Sun Dec 26 12:34:12 CET 2004
>>>>> "BDR" == Prof Brian Ripley <ripley at stats.ox.ac.uk>
>>>>> on Sun, 26 Dec 2004 10:03:30 +0000 (GMT) writes:
BDR> R-devel now has some improved versions of read.table
BDR> and write.table. For a million-row data frame
BDR> containing one number, one factor with few levels and
BDR> one logical column, a 56Mb object.
BDR> generating it takes 4.5 secs.
BDR> calling summary() on it takes 2.2 secs.
BDR> writing it takes 8 secs and an additional 10Mb.
BDR> saving it in .rda format takes 4 secs.
BDR> reading it naively takes 28 secs and an additional
BDR> reading it carefully (using nrows, colClasses and
BDR> comment.char) takes 16 secs and an additional 150Mb
BDR> (56Mb of which is for the object read in). (The
BDR> overhead of read.table over scan was about 2 secs,
BDR> mainly in the conversion back to a factor.)
BDR> loading from .rda format takes 3.4 secs.
BDR> [R 2.0.1 read in 23 secs using an additional 210Mb, and
BDR> wrote in 50 secs using an additional 450Mb.]
Thanks a lot Brian (for this and much more)!
I wish you continued merry holidays!
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