nonzero-methods {Ringo} | R Documentation

## Methods for Function nonzero

### Description

Auxiliary functions to retrieve the indices of non-zero elements in sparse matrices.

### Value

A two-column matrix. Each row gives the row and column index of a non-zero element in the supplied matrix `x`.

### Methods

x = "dgCMatrix"

  returns the indices of non-zero elements in matrices of class `dgCMatrix`

x = "matrix.csr"

  returns the indices of non-zero elements in matrices of class `matrix.csr`

x = "matrix"

  returns the indices of non-zero elements in matrices of base class `matrix`; equivalent to `which(x != 0, arr.ind=TRUE)`

### Note

Originally we used the `matrix.csr` class from SparseM, but we have switched to the class `dgCMatrix` from package Matrix, as that package is part of the R distribution bundle now.

The idea is to have a function similar to `which(x != 0, arr.ind=TRUE)` if `x` is a matrix.

### See Also

`dgCMatrix-class`

### Examples

      (A <- matrix(c(0,0,0,0,0,1,0,0,0,0,0,0,0,0,-34),
                   nrow=5, byrow=TRUE))
      str(A.dgc <- as(A, "dgCMatrix"))
      nonzero(A.dgc)
      A2.dgc <- cbind(A.dgc, A.dgc)
      as.matrix(A2.dgc)
      nonzero(A2.dgc)

[Package Ringo version 1.58.0 Index]