big_copy {bigstatsr}  R Documentation 
Deep copy of a Filebacked Big Matrix with possible subsetting. This should also work for any matrixlike object.
big_copy(
X,
ind.row = rows_along(X),
ind.col = cols_along(X),
type = typeof(X),
backingfile = tempfile(),
block.size = block_size(length(ind.row)),
is_read_only = FALSE
)
X 
Could be any matrixlike object. 
ind.row 
An optional vector of the row indices that are used. If not specified, all rows are used. Don't use negative indices. 
ind.col 
An optional vector of the column indices that are used. If not specified, all columns are used. Don't use negative indices. 
type 
Type of the Filebacked Big Matrix (default is

backingfile 
Path to the file storing the Big Matrix on disk. An extension ".bk" will be automatically added. Default stores in the temporary directory. 
block.size 
Maximum number of columns read at once. Default uses block_size. 
is_read_only 
Whether the FBM is readonly? Default is 
A copy of X
as a new FBM object.
X < FBM(10, 10, init = 1:100)
X[]
X2 < big_copy(X, ind.row = 1:5)
X2[]
mat < matrix(101:200, 10)
X3 < big_copy(mat, type = "double") # as_FBM() would be faster here
X3[]
X.code < big_attachExtdata()
class(X.code)
X2.code < big_copy(X.code)
class(X2.code)
all.equal(X.code[], X2.code[])