R: Extract one cell from each row (column) of a matrix-like...

colCollapse,xgCMatrix-method {sparseMatrixStats}

R Documentation

Extract one cell from each row (column) of a matrix-like object

Description

Extract one cell from each row (column) of a matrix-like object.

Usage

## S4 method for signature 'xgCMatrix'
colCollapse(x, idxs, cols = NULL)

## S4 method for signature 'xgCMatrix'
rowCollapse(x, idxs, rows = NULL)

Arguments

`x`	An NxK matrix-like object.
`idxs`	An index `vector` with the position to extract. It is recycled to match the number of rows (column)
`cols`	A `vector` indicating the subset of rows (and/or columns) to operate over. If `NULL`, no subsetting is done.
`rows`	A `vector` indicating the subset of rows (and/or columns) to operate over. If `NULL`, no subsetting is done.

Details

The S4 methods for x of type matrix, array, or numeric call matrixStats::rowCollapse / matrixStats::colCollapse.

Value

Returns a numeric vector of length N (K).

Examples

mat <- matrix(rnorm(15), nrow = 5, ncol = 3)
  mat[2, 1] <- NA
  mat[3, 3] <- Inf
  mat[4, 1] <- 0
  
  print(mat)
  
  rowCollapse(mat, idxs = 2)
  rowCollapse(mat, idxs = c(1,1,2,3,2))
  
  colCollapse (mat, idxs = 4)

[Package sparseMatrixStats version 1.2.1 Index]