Hi ff users and Jens,
I am using the ff package and it has been working great. Recently I
noticed an unexpected behavior in the ff package -- when I save an ff
matrix on one machine to an NFS drive and load it on another machine from
the save NFS drive, I got quote a lot of zeros in the matrix. The
following code reproduces the error
mat = matrix(1:25, 5)
matFF = ff(mat, dim=dim(mat), dimnames = dimnames(mat),
dimorder = c(2,1),
filename= "~/m.ff", overwrite=TRUE)
save(matFF, file = "~/mat.ff.rda")
load(file = "~/mat.ff.rda")
open(matFF)
matFF
If I execute all the six lines at one machine. Everything works fine.
However, when I only execute the last three line at another machine, I got
> matFF
ff (open) integer length=25 (25) dim=c(5,5) dimorder=c(2,1)
[,1] [,2] [,3] [,4] [,5]
[1,] 0 0 0 0 0
[2,] 0 0 0 0 0
[3,] 0 0 0 0 0
[4,] 0 0 0 0 0
[5,] 0 0 0 0 0
If the matrix is larger, say mat = matrix(1:20000, 5), I would get the
following -- dozens of zeros at the end.
ff (open) integer length=20000 (20000) dim=c(5,4000) dimorder=c(2,1)
[,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,3993] [,3994]
[,3995] [,3996] [,3997] [,3998] [,3999] [,4000]
[1,] 1 6 11 16 21 26 31 36 : 19961 19966
19971 19976 19981 19986 19991 19996
[2,] 2 7 12 17 22 27 32 37 : 19962 19967
19972 19977 19982 19987 19992 19997
[3,] 3 8 13 18 23 28 33 38 : 19963 19968
19973 19978 19983 19988 19993 19998
[4,] 4 9 14 19 24 29 34 39 : 19964 19969
19974 19979 19984 19989 19994 19999
[5,] 5 10 15 20 25 30 35 40 : 0 0
0 0 0 0 0 0
I tried set caching = "mmeachflush" in the ff function but it doesn't
help. My computing enrionment is linux 64 bit, R 2.10, ff 2.1.
If you know what causes the issue or how to solve it, please let me know.
I highly appreciate.
Jeff
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