Hi Jens,
Thanks for the example! I can see that you can change the 'filename' attribute
for a ff object one-by-one, but is there a way to issue one command that will
automatically change the attribute to all the ff objects in your workspace, as
you can imagine when I have large number of objects like this, doing one-by-one
is cumbersome? After all, all it needs to change is the folder path, right?
May be this is a too wishful thinking :-)
Best,
Tao
On Friday, June 26, 2015 3:31 AM, Jens Oehlschlägel
<jens.oehlschlae...@truecluster.com> wrote:
Tao,
I do assume that the ff-files are still at some location and not deleted
by a finalizer. The following explains how to manipulate file locations
with ff and ffdf objects.
Kind regards
jens
library(ff)
path1 <- "c:/tmp"
path2 <- "c:/tmp2"
# create ffdf,
# using non-standard path sets finalizer to 'close' instead of 'delete'
fdf1 <- as.ffdf(iris, col_args=list(pattern=file.path(path1,"iris")))
# let's copy the old metadata (but not the files, useclone for that)
# using ffs hybrid copying semantics
fdf2 <- fdf1
# note both are open
is.open(fdf1)
is.open(fdf2)
# close the files
close(fdf1)
# and note that
is.open(fdf1)
is.open(fdf2)
# the magic has kept physical metadata in synch even in the copy
# (virtual metadata is not kept in synch
# which allows different virtual views into the same files
# not unlike SQL VIEWs virtualize dastabase TABLEs)
# filename on a ffdf
filename(fdf2)
# is a shortcut for
lapply(physical(fdf2), filename)
# so filename is a physical attribute
# actually moving the files can be done with the filename<- method
lapply(physical(fdf2), function(x)filename(x) <- sub(path1, path2,
filename(x)))
# check this
filename(fdf1)
filename(fdf2)
# filename on ff
filename(fdf1$Species)
# is a shortcut for
attr(attr(fdf1$Species, "physical"), "filename")
# and if you directly manipulate this attribute
# you circummvent the filename method
# and the file itself will not be moved
attr(attr(fdf1$Species, "physical"), "filename") <- sub(path2, path1,
filename(fdf1$Species))
# now the metadata points to a different location
filename(fdf1$Species)
# note that this physical attribute was also changed
# for the copy
filename(fdf2$Species)
# of course you can fix the erroneous metadata by
attr(attr(fdf1$Species, "physical"), "filename") <- sub(path1, path2,
filename(fdf1$Species))
# or for all columns in a ffdf by
lapply(physical(fdf2), function(x)attr(attr(x, "physical"), "filename")
<- sub(path2, path1, filename(x)))
# now we have your situation with broken metadata
open(fdf2)
# and can fix that by
lapply(physical(fdf2), function(x)attr(attr(x, "physical"), "filename")
<- sub(path1, path2, filename(x)))
# check
open(fdf2)
Am 26.06.2015 um 01:04 schrieb Shi, Tao:
> Hi all,
>
> I'm new to "ff" package through the using Bioconductor package "crlmm". Here
> is my problem:
>
> I've created a few R objects (e.g. an CNSet) using crlmm based on my data and
> save them in a .RData file. crlmm heavily uses ff package to store results
> on a local folder. For certain reasons, I have moved the ff output folder to
> somewhere else. Now when I go back to R, I can't open those CNSet, for
> example, anymore, as the file has a property still storing the old ff output
> folder path.
>
> My question is: is there a quick way to change these paths to the new one, so
> I don't have to re-run the own analysis.
>
> Many thanks!
>
> Tao
>
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