col_nnz: Number of zeros

In m20ty/matkot: Make Matrices Fun!

Number of zeros

Description

Find the number of non-zero elements in a matrix per row, per column or in total. In the case of sparse matrices (class dgTMatrix, dgCMatrix or dgRMatrix), this is much faster than using apply and/or sum. Note there already exists a function nnzero in the Matrix package that finds the number of non-zero elements in a sparse matrix, but nnz is faster.

Usage

col_nnz(mat)

row_nnz(mat)

nnz(mat)

Arguments

mat	A matrix. May be sparse (i.e. of class dgTMatrix, dgCMatrix or dgRMatrix).

Value

An integer or named integer vector.

Examples

mat <- matrix(rbinom(900, 1, 0.1), 30, 30)
col_nnz(mat)
rownames(mat) <- replicate(30, paste(sample(letters, 10), collapse = ''))
row_nnz(mat)
nnz(mat)
mat <- as(mat, 'dgCMatrix')
row_nnz(mat)
nnz(mat)

m20ty/matkot documentation built on July 1, 2023, 8:11 p.m.