R: Methods for "[": Extraction or Subsetting in Package 'Matrix'

[-methods {Matrix} | R Documentation

## Methods for "[": Extraction or Subsetting in Package 'Matrix'

### Description

Methods for `"["`, i.e., extraction or subsetting mostly of matrices, in package Matrix.

### Methods

There are more than these:

x = "Matrix", i = "missing", j = "missing", drop= "ANY"

  ...

x = "Matrix", i = "numeric", j = "missing", drop= "missing"

  ...

x = "Matrix", i = "missing", j = "numeric", drop= "missing"

  ...

x = "dsparseMatrix", i = "missing", j = "numeric", drop= "logical"

  ...

x = "dsparseMatrix", i = "numeric", j = "missing", drop= "logical"

  ...

x = "dsparseMatrix", i = "numeric", j = "numeric", drop= "logical"

  ...

### See Also

`[<–methods` for subassignment to `"Matrix"` objects. `Extract` about the standard extraction.

### Examples

    str(m <- Matrix(round(rnorm(7*4),2), nrow = 7))
    stopifnot(identical(m, m[]))
    m[2, 3]   # simple number
    m[2, 3:4] # simple numeric of length 2
    m[2, 3:4, drop=FALSE] # sub matrix of class 'dgeMatrix'
    ## rows or columns only:
    m[1,]     # first row, as simple numeric vector
    m[,1:2]   # sub matrix of first two columns

    showMethods("[", inherited = FALSE)

[Package Matrix version 1.1-4 Index]