[R] Reading File Sizes: very slow!

[Bill Dunlap]

On my Windows 10 laptop I see evidence of the operating system caching
information about recently accessed files.  This makes it hard to say how
the speed might be improved.  Is there a way to clear this cache?

> system.time(L1 <- size.f.pkg(R.home("library")))
   user  system elapsed
   0.48    2.81   30.42
> system.time(L2 <- size.f.pkg(R.home("library")))
   user  system elapsed
   0.35    1.10    1.43
> identical(L1,L2)
[1] TRUE
> length(L1)
[1] 30
> length(dir(R.home("library"),recursive=TRUE))
[1] 12949

On Sat, Sep 25, 2021 at 8:12 AM Leonard Mada via R-help <
r-help using r-project.org> wrote:

> Dear List Members,
>
>
> I tried to compute the file sizes of each installed package and the
> process is terribly slow.
>
> It took ~ 10 minutes for 512 packages / 1.6 GB total size of files.
>
>
> 1.) Package Sizes
>
>
> system.time({
>          x = size.pkg(file=NULL);
> })
> # elapsed time: 509 s !!!
> # 512 Packages; 1.64 GB;
> # R 4.1.1 on MS Windows 10
>
>
> The code for the size.pkg() function is below and the latest version is
> on Github:
>
> https://github.com/discoleo/R/blob/master/Stat/Tools.CRAN.R
>
>
> Questions:
> Is there a way to get the file size faster?
> It takes long on Windows as well, but of the order of 10-20 s, not 10
> minutes.
> Do I miss something?
>
>
> 1.b.) Alternative
>
> It came to my mind to read first all file sizes and then use tapply or
> aggregate - but I do not see why it should be faster.
>
> Would it be meaningful to benchmark each individual package?
>
> Although I am not very inclined to wait 10 minutes for each new try out.
>
>
> 2.) Big Packages
>
> Just as a note: there are a few very large packages (in my list of 512
> packages):
>
> 1  123,566,287               BH
> 2  113,578,391               sf
> 3  112,252,652            rgdal
> 4   81,144,868           magick
> 5   77,791,374 openNLPmodels.en
>
> I suspect that sf & rgdal have a lot of duplicated data structures
> and/or duplicate code and/or duplicated libraries - although I am not an
> expert in the field and did not check the sources.
>
>
> Sincerely,
>
>
> Leonard
>
> =======
>
>
> # Package Size:
> size.f.pkg = function(path=NULL) {
>      if(is.null(path)) path = R.home("library");
>      xd = list.dirs(path = path, full.names = FALSE, recursive = FALSE);
>      size.f = function(p) {
>          p = paste0(path, "/", p);
>          sum(file.info(list.files(path=p, pattern=".",
>              full.names = TRUE, all.files = TRUE, recursive = TRUE))$size);
>      }
>      sapply(xd, size.f);
> }
>
> size.pkg = function(path=NULL, sort=TRUE, file="Packages.Size.csv") {
>      x = size.f.pkg(path=path);
>      x = as.data.frame(x);
>      names(x) = "Size"
>      x$Name = rownames(x);
>      # Order
>      if(sort) {
>          id = order(x$Size, decreasing=TRUE)
>          x = x[id,];
>      }
>      if( ! is.null(file)) {
>          if( ! is.character(file)) {
>              print("Error: Size NOT written to file!");
>          } else write.csv(x, file=file, row.names=FALSE);
>      }
>      return(x);
> }
>
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