big_cprodVec | R Documentation |
Cross-product between a Filebacked Big Matrix and a vector.
big_cprodVec( X, y.row, ind.row = rows_along(X), ind.col = cols_along(X), center = NULL, scale = NULL, ncores = 1 )
X |
An object of class FBM. |
y.row |
A vector of same size as |
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. |
center |
Vector of same length of |
scale |
Vector of same length of |
ncores |
Number of cores used. Default doesn't use parallelism. You may use nb_cores. |
X^T \cdot y.
X <- big_attachExtdata() n <- nrow(X) m <- ncol(X) y <- rnorm(n) test <- big_cprodVec(X, y) # vector true <- crossprod(X[], y) # one-column matrix all.equal(test, as.numeric(true)) # subsetting ind.row <- sample(n, n/2) ind.col <- sample(m, m/2) tryCatch(test2 <- big_cprodVec(X, y, ind.row, ind.col), error = function(e) print(e)) # returns an error. You need to use the subset of y: test2 <- big_cprodVec(X, y[ind.row], ind.row, ind.col) true2 <- crossprod(X[ind.row, ind.col], y[ind.row]) all.equal(test2, as.numeric(true2))
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