Dear all
I am having trouble with subsetting an ffdf object, hopefully somebody can
help...
I have an index, which is a ff object of vmode "logical":
> index.SAS
ff (open) logical length=4977231 (4977231)
[1] [2] [3] [4] [5] [6] [7] [8]
[4977224] [4977225] [4977226] [4977227] [4977228] [4977229]
TRUE TRUE TRUE TRUE TRUE TRUE TRUE TRUE
: TRUE TRUE TRUE TRUE TRUE TRUE
[4977230] [4977231]
TRUE TRUE
I would like to use this index to subset the ffdf object "data.SAS". The number
of rows in data.SAS equals the length of index.SAS. However, the command
> Missing.data <- subset(data.SAS, !index.SAS)
gives me the following error:
Error in ffdf(x = x) : ffdf components must be atomic ff objects
A similar command also results in an error:
> Missing.data <- data.SAS[!index.SAS,]
Error: vmode(index) == "integer" is not TRUE
I do not want to use "index.SAS[]" (which works in many cases, but sometimes
crashes), because - as far as I understand - this will cause trouble with
really large index vectors (I would prefer using ff objects).
So I came up with the following syntax, which seems to work:
> Missing.data <- data.SAS[ffwhich(index.SAS,index.SAS==FALSE),]
...I am just not sure if this is the right approach.
I am running
platform i386-w64-mingw32
arch i386
os mingw32
system i386, mingw32
status
major 3
minor 0.3
year 2014
month 03
day 06
svn rev 65126
language R
version.string R version 3.0.3 (2014-03-06)
nickname Warm Puppy
with ffbase_0.11.3 and ff_2.2-12
Many thanks in advance
Christian
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