Select zero columns — selectzerocols

Matrices with columns containing all zeroes are not invertible (singular). To diagnose this problem, it is useful to find the zero columns of a singular matrix. This function selects (extracts) only the zero columns of a matrix.

Usage

selectzerocols_byname(a, tol = 1e-06)

Arguments

a: A matrix or a list of matrices.
tol: The allowable deviation from 0 for any element.

Value

a with only zero columns selected.

Details

A column is said to be a zero column if all elements are within tol of zero.

Examples

m <- matrix(c(1, 0, 1,
              1, 0, 1),
            dimnames = list(c("r1", "r2"), c("c1", "c2", "c3")), 
            nrow = 2, ncol = 3, byrow = TRUE) %>% 
  setrowtype("rows") %>% setcoltype("cols")
selectzerocols_byname(m)
#>    c2
#> r1  0
#> r2  0
#> attr(,"rowtype")
#> [1] "rows"
#> attr(,"coltype")
#> [1] "cols"