Transpose an FBM — big_transpose • bigstatsr

This function implements a simple cache-oblivious algorithm for the transposition of a Filebacked Big Matrix.

big_transpose(X, backingfile = tempfile(tmpdir = getOption("FBM.dir")))

Arguments

X: An object of class FBM.
backingfile: Path to the file storing the FBM data on disk. An extension ".bk" will be automatically added. Default stores in the temporary directory, which you can change using global option "FBM.dir".

Value

The new transposed FBM. Dimensions and type are automatically determined from the input FBM.

Examples

X <- FBM(6, 5, init = rnorm(30))
X[]
#>            [,1]         [,2]       [,3]       [,4]       [,5]
#> [1,]  0.1066472 -0.350078968  0.3014073  1.6228060  1.3485703
#> [2,] -1.0103989  1.681213501 -1.6633137  0.8911158  0.1358977
#> [3,]  1.1788924 -2.290655613 -0.4913255 -0.5310150  1.5544532
#> [4,] -1.8382279 -0.004754315 -0.3598196  1.0204832 -0.1388967
#> [5,] -1.2122184 -1.556176609  1.6691504  1.1152850 -0.1206802
#> [6,] -0.7722889  0.699863428  0.9413492  0.1955967  0.7522782
Xt <- big_transpose(X)
identical(t(X[]), Xt[])
#> [1] TRUE