Deep copy of a Filebacked Big Matrix with possible subsetting. This should also work for any matrix-like 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)),
)

## Arguments

X Could be any matrix-like object. An optional vector of the row indices that are used. If not specified, all rows are used. Don't use negative indices. An optional vector of the column indices that are used. If not specified, all columns are used. Don't use negative indices. Type of the Filebacked Big Matrix (default is double). Either "double" (double precision -- 64 bits) "float" (single precision -- 32 bits) "integer" "unsigned short": can store integer values from 0 to 65535. It has vocation to become the basis for a FBM.code65536. "raw" or "unsigned char": can store integer values from 0 to 255. It is the basis for class FBM.code256 in order to access 256 arbitrary different numeric values. It is used in package bigsnpr. Path to the file storing the Big Matrix on disk. An extension ".bk" will be automatically added. Default stores in the temporary directory. Maximum number of columns read at once. Default uses block_size. Whether the FBM is read-only? Default is FALSE.

## Value

A copy of X as a new FBM object.

## Examples

X <- FBM(10, 10, init = 1:100)
X[]#>       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#>  [1,]    1   11   21   31   41   51   61   71   81    91
#>  [2,]    2   12   22   32   42   52   62   72   82    92
#>  [3,]    3   13   23   33   43   53   63   73   83    93
#>  [4,]    4   14   24   34   44   54   64   74   84    94
#>  [5,]    5   15   25   35   45   55   65   75   85    95
#>  [6,]    6   16   26   36   46   56   66   76   86    96
#>  [7,]    7   17   27   37   47   57   67   77   87    97
#>  [8,]    8   18   28   38   48   58   68   78   88    98
#>  [9,]    9   19   29   39   49   59   69   79   89    99
#> [10,]   10   20   30   40   50   60   70   80   90   100X2 <- big_copy(X, ind.row = 1:5)
X2[]#>      [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#> [1,]    1   11   21   31   41   51   61   71   81    91
#> [2,]    2   12   22   32   42   52   62   72   82    92
#> [3,]    3   13   23   33   43   53   63   73   83    93
#> [4,]    4   14   24   34   44   54   64   74   84    94
#> [5,]    5   15   25   35   45   55   65   75   85    95
mat <- matrix(101:200, 10)
X3 <- big_copy(mat, type = "double")  # as_FBM() would be faster here
X3[]#>       [,1] [,2] [,3] [,4] [,5] [,6] [,7] [,8] [,9] [,10]
#>  [1,]  101  111  121  131  141  151  161  171  181   191
#>  [2,]  102  112  122  132  142  152  162  172  182   192
#>  [3,]  103  113  123  133  143  153  163  173  183   193
#>  [4,]  104  114  124  134  144  154  164  174  184   194
#>  [5,]  105  115  125  135  145  155  165  175  185   195
#>  [6,]  106  116  126  136  146  156  166  176  186   196
#>  [7,]  107  117  127  137  147  157  167  177  187   197
#>  [8,]  108  118  128  138  148  158  168  178  188   198
#>  [9,]  109  119  129  139  149  159  169  179  189   199
#> [10,]  110  120  130  140  150  160  170  180  190   200
X.code <- big_attachExtdata()
class(X.code)#> [1] "FBM.code256"
#> attr(,"package")
#> [1] "bigstatsr"X2.code <- big_copy(X.code)
class(X2.code)#> [1] "FBM.code256"
#> attr(,"package")
#> [1] "bigstatsr"all.equal(X.code[], X2.code[])#> [1] TRUE