# Save R and ff objects `ffsave` writes an external representation of R and ff objects to an `ffarchive`. The objects can be read back from the file at a later date by using the function `ffload`. ```r ffsave(... , list = character(0L) , file = stop("'file' must be specified") , envir = parent.frame() , rootpath = NULL , add = FALSE , move = FALSE , compress = !move , compression_level = 6 , precheck=TRUE ) ffsave.image(file = stop("'file' must be specified"), safe = TRUE, ...) ``` ## Arguments - ``...``: For `ffsave` the names of the objects to be saved (as symbols or character strings), for `ffsave.image` further arguments passed to `ffsave` - `list`: A character vector containing the names of objects to be saved. - `file`: A name for the the `ffarchive`, i.e. the two files `.RData` and `.ffData` - `envir`: environment to search for objects to be saved. - `add`: logical indicating whether the objects shall be added to the `ffarchive` (in this case `rootpath` is taken from an existing archive) - `move`: logical indicating whether ff files shall be moved instead of copied into the `.ffData` - `compress`: logical specifying whether saving to a named file is to use compression. - `compression_level`: compression level passed to `zip`, default 6 - `rootpath`: optional path component that all **all** ff files share and that can be dropped/replaced when calling `ffload` - `precheck`: logical: should the existence of the objects be checked before starting to save (and in particular before opening the file/connection)? - `safe`: logical. If `TRUE`, a temporary file is used for creating the saved workspace. The temporary file is renamed to `.ffData` if the save succeeds. This preserves an existing workspace `.ffData` if the save fails, but at the cost of using extra disk space during the save. ## Details `ffsave` stores objects and ff files in an `ffarchive` named ``: i.e. it saves all specified objects via `save` in a file named `.RData` and saves all ff files related to these objects in a zipfile named `.ffData` using an external `zip` utility. By default files are stored relative to the `rootpath="\"} and will be restored relative to \code{"\"` (in its original location). By providing a partial path prefix via argument `rootpath` the files are stored relative to this `rootpath`. The `rootpath` is stored in the `.RData` with the name `.ff.rootpath`. I.e. even if the ff objects were saved with argument `rootpath` to `ffsave`, `ffload` by default restores in the original location. By using argument `rootpath` to `ffload` you can restore relative to a different `rootpath` (and using argument `rootpath` to `ffsave` gave you shorter relative paths) By using argument `add` in `ffsave` you can add more objects to an existing `ffarchive` and by using argument `list` in `ffload` you can selectively restore objects. The content of the `ffarchive` can be inspected using `ffinfo` before actually loading any of the objects. The `ffarchive` can be deleted from disk using `ffdrop`. ## Returns a character vector with messages returned from the `zip` utility (one for each ff file zipped) ## Author(s) Jens Oehlschlägel ## Note The ff files are not platform-independent with regard to byte order. For large files and the zip64 format use `zip 3.0` and `unzip 6.0` from [https://infozip.sourceforge.net/](https://infozip.sourceforge.net/). ## See Also `ffinfo` for inspecting the content of the `ffarchive` `ffload` for loading all or some of the `ffarchive` `ffdrop` for deleting one or more `ffarchives` ## Examples ```r ## Not run: message("let's create some ff objects") n <- 8e3 a <- ff(sample(n, n, TRUE), vmode="integer", length=n, filename="d:/tmp/a.ff") b <- ff(sample(255, n, TRUE), vmode="ubyte", length=n, filename="d:/tmp/b.ff") x <- ff(sample(255, n, TRUE), vmode="ubyte", length=n, filename="d:/tmp/x.ff") y <- ff(sample(255, n, TRUE), vmode="ubyte", length=n, filename="d:/tmp/y.ff") z <- ff(sample(255, n, TRUE), vmode="ubyte", length=n, filename="d:/tmp/z.ff") df <- ffdf(x=x, y=y, z=z) rm(x,y,z) message("save all of them") ffsave.image("d:/tmp/x") str(ffinfo("d:/tmp/x")) message("save some of them with shorter relative pathnames ...") ffsave(a, b, file="d:/tmp/y", rootpath="d:/tmp") str(ffinfo("d:/tmp/y")) message("... and add others later") ffsave(df, add=TRUE, file="d:/tmp/y", rootpath="d:/tmp") str(ffinfo("d:/tmp/y")) message("... and add others later") system.time(ffsave(a, file="d:/tmp/z", move=TRUE)) ffinfo("d:/tmp/z") message("let's delete/close/remove all objects") close(a) # no file anymore, since we moved a into the ffarchive delete(b, df) rm(df, a, b, n) message("prove it") ls() message("restore all but ff files in a different directory") system.time(ffload("d:/tmp/x", rootpath="d:/tmp2")) lapply(ls(), function(i)filename(get(i))) delete(a, b, df) rm(df, a, b) ffdrop(c("d:/tmp/x", "d:/tmp/y", "d:/tmp/z")) ## End(Not run) ```

ffsave.rd function