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

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))
#> Formal class 'dgeMatrix' [package "Matrix"] with 4 slots
#>   ..@ Dim     : int [1:2] 7 4
#>   ..@ Dimnames:List of 2
#>   .. ..$ : NULL
#>   .. ..$ : NULL
#>   ..@ x       : num [1:28] 0.47 0.5 0.89 0.28 1.01 -2.07 1.19 -0.72 0.17 0.92 ...
#>   ..@ factors : list()
stopifnot(identical(m, m[]))
m[2, 3]   # simple number
#> [1] -0.46
m[2, 3:4] # simple numeric of length 2
#> [1] -0.46 -1.15
m[2, 3:4, drop=FALSE] # sub matrix of class 'dgeMatrix'
#> 1 x 2 Matrix of class "dgeMatrix"
#>       [,1]  [,2]
#> [1,] -0.46 -1.15
## rows or columns only:
m[1,]     # first row, as simple numeric vector
#> [1]  0.47 -0.72 -2.32 -1.48
m[,1:2]   # sub matrix of first two columns
#> 7 x 2 Matrix of class "dgeMatrix"
#>       [,1]  [,2]
#> [1,]  0.47 -0.72
#> [2,]  0.50  0.17
#> [3,]  0.89  0.92
#> [4,]  0.28 -1.67
#> [5,]  1.01  0.45
#> [6,] -2.07  0.48
#> [7,]  1.19  0.76

showMethods("[", inherited = FALSE)
#> Function: [ (package base)
#> x="Matrix", i="ANY", j="NULL", drop="ANY"
#> x="Matrix", i="NULL", j="ANY", drop="ANY"
#> x="Matrix", i="NULL", j="NULL", drop="ANY"
#> x="Matrix", i="index", j="index", drop="logical"
#> x="Matrix", i="index", j="index", drop="missing"
#> x="Matrix", i="index", j="missing", drop="logical"
#> x="Matrix", i="index", j="missing", drop="missing"
#> x="Matrix", i="lMatrix", j="missing", drop="missing"
#> x="Matrix", i="matrix", j="missing", drop="missing"
#> x="Matrix", i="missing", j="index", drop="logical"
#> x="Matrix", i="missing", j="index", drop="missing"
#> x="Matrix", i="missing", j="missing", drop="logical"
#> x="Matrix", i="missing", j="missing", drop="missing"
#> x="Matrix", i="nMatrix", j="missing", drop="missing"
#> x="abIndex", i="index", j="ANY", drop="ANY"
#> x="nonStructure", i="ANY", j="ANY", drop="ANY"
#> x="sparseVector", i="NULL", j="ANY", drop="ANY"
#> x="sparseVector", i="index", j="missing", drop="missing"
#> x="sparseVector", i="lsparseVector", j="missing", drop="missing"
#> x="sparseVector", i="missing", j="missing", drop="missing"
#> x="sparseVector", i="nsparseVector", j="missing", drop="missing"
#>