Hi, FYI, I just notice that on Windows (but not Linux) it is orders of magnitude (below it's 50x) faster to serialize() and object to a temporary file and then read it back, than to serialize to an object directly. This has for instance impact on how fast digest::digest() can provide a checksum.
Example: x <- 1:1e7; t1 <- system.time(raw1 <- serialize(x, connection=NULL)); print(t1); # user system elapsed # 174.23 129.35 304.70 ## 5 minutes t2 <- system.time(raw2 <- serialize2(x, connection=NULL)); print(t2); # user system elapsed # 2.19 0.18 5.72 ## 5 seconds print(t1/t2); # user system elapsed # 79.55708 718.61111 53.26923 stopifnot(identical(raw1, raw2)); where serialize2() is serialize():ing to file and reading the results back: serialize2 <- function(object, connection, ...) { if (is.null(connection)) { # It is faster to serialize to a temporary file and read it back pathname <- tempfile(); con <- file(pathname, open="wb"); on.exit({ if (!is.null(con)) close(con); if (file.exists(pathname)) file.remove(pathname); }); base::serialize(object, connection=con, ...); close(con); con <- NULL; fileSize <- file.info(pathname)$size; readBin(pathname, what="raw", n=fileSize); } else { base::serialize(object, connection=connection, ...); } } # serialize2() The above benchmarking was done in a fresh R v2.7.1 session on WinXP Pro: > sessionInfo() R version 2.7.1 Patched (2008-06-27 r46012) i386-pc-mingw32 locale: LC_COLLATE=English_United States.1252;LC_CTYPE=English_United States.1252;LC_MON ETARY=English_United States.1252;LC_NUMERIC=C;LC_TIME=English_United States.1252 attached base packages: [1] stats graphics grDevices utils datasets methods base When I do the same on a Linux machine there is no difference: > sessionInfo() R version 2.7.1 (2008-06-23) x86_64-unknown-linux-gnu locale: LC_CTYPE=en_US.UTF-8;LC_NUMERIC=C;LC_TIME=en_US.UTF-8;LC_COLLATE=en_US.UTF-8;LC_MONETARY=C;LC_MESSAGES=en_US.UTF-8;LC_PAPER=en_US.UTF-8;LC_NAME=C;LC_ADDRESS=C;LC_TELEPHONE=C;LC_MEASUREMENT=en_US.UTF-8;LC_IDENTIFICATION=C attached base packages: [1] stats graphics grDevices utils datasets methods base Is there an obvious reason (and an obvious fix) for this? Cheers Henrik ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel