questions on the ff package
Dear Jeff, This is not exactly what you are asking, but what I do is close the object, save it as RData, and then when I need to load the RData. The RData objects themselves are very small. Best, R.
On Wed, Nov 25, 2009 at 2:28 AM, Hao Cen <hcen at andrew.cmu.edu> wrote:
Hi, I have two questions on using the ff package and wonder if anyone who used ff can share some thoughts. I need to save a matrix as a memory-mapped file and load it back later. To save the matrix, I use mat = matrix(1:20, 4, 5) matFF = ff(mat, dim=dim(mat), filename="~/a.mat", overwrite=TRUE, dimnames = dimnames(mat)) To load it back, I use matFF2 = ff(vmode = "double", dim= ???, filename="~/a.mat", overwrite=F) However, I don't always know the dimension when loading the matrix back. If I miss the dim attributes, ff will return it as vector. Is there a way to load the matrix without specifying the dimension? The second question is that the matrix may grow in terms of the number of rows. I would like to synchronize the change to the memory-mapped file. Is there an efficient way to do this? Thanks Jeff
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