Compute sample or population variances for each row of a dense or sparse
matrix without densifying sparse input.
Usage
fast_row_vars(x, unbiased = TRUE)
Arguments
- x
A matrix or a `Matrix` sparse matrix.
- unbiased
Whether to compute the unbiased sample variance (the
default) instead of the population variance.
Value
A numeric vector of row variances. Row names are retained when
available. Matrices with zero columns return `NA` for every row. A
one-column matrix returns `NA` for sample variance and `0` for population
variance.
Examples
fast_row_vars(matrix(c(1, 2, 3, 4), nrow = 2))
#> [1] 2 2
