Remove empty (all-zero) columns

remove_empty() removes all-zero columns from sparse and dense matrices.

Usage

remove_empty(x)

# S3 method for CsparseMatrix
remove_empty(x)

# S3 method for matrix
remove_empty(x)

Arguments

x

A matrix or CsparseMatrix.

Value

x with all-zero columns removed.

Details

remove_empty() is an S3 generic with methods for:

• CsparseMatrix

• matrix

Examples

# Create a sparse matrix with constant columns
x <- Matrix::rsparsematrix(10, 3, 0.1)
x <- cbind(x, 0)
colnames(x) <- paste0("x", 1:4)
# Print x
x
#> 10 x 4 sparse Matrix of class "dgCMatrix"
#>         x1 x2   x3 x4
#>  [1,] .     .  .    .
#>  [2,] .     .  .    .
#>  [3,] 0.84  .  .    .
#>  [4,] .     .  .    .
#>  [5,] .     .  .    .
#>  [6,] .     . -1.3  .
#>  [7,] .     .  .    .
#>  [8,] 0.51  .  .    .
#>  [9,] .     .  .    .
#> [10,] .     .  .    .

# Same matrix in dense format
xdense <- as.matrix(x)

# Drop empty columns
remove_empty(x)
#> 10 x 2 sparse Matrix of class "dgCMatrix"
#>         x1   x3
#>  [1,] .     .  
#>  [2,] .     .  
#>  [3,] 0.84  .  
#>  [4,] .     .  
#>  [5,] .     .  
#>  [6,] .    -1.3
#>  [7,] .     .  
#>  [8,] 0.51  .  
#>  [9,] .     .  
#> [10,] .     .  
remove_empty(xdense)
#>         x1   x3
#>  [1,] 0.00  0.0
#>  [2,] 0.00  0.0
#>  [3,] 0.84  0.0
#>  [4,] 0.00  0.0
#>  [5,] 0.00  0.0
#>  [6,] 0.00 -1.3
#>  [7,] 0.00  0.0
#>  [8,] 0.51  0.0
#>  [9,] 0.00  0.0
#> [10,] 0.00  0.0