Matrix (version 1.7-1)

sparseVector: Sparse Vector Construction from Nonzero Entries

Description

User friendly construction of sparse vectors, i.e., objects inheriting from class sparseVector, from indices and values of its non-zero entries.

Usage

sparseVector(x, i, length)

Value

a sparse vector, i.e., inheriting from class

sparseVector.

Arguments

x

vector of the non zero entries; may be missing in which case a "nsparseVector" will be returned.

i

integer vector (of the same length as x) specifying the indices of the non-zero (or non-TRUE) entries of the sparse vector.

length

length of the sparse vector.

Author

Martin Maechler

Details

zero entries in x are dropped automatically, analogously as drop0() acts on sparse matrices.

See Also

sparseMatrix() constructor for sparse matrices; the class sparseVector.

Examples

 
library(utils, pos = "package:base", verbose = FALSE)

str(sv <- sparseVector(x = 1:10, i = sample(999, 10), length=1000))

sx <- c(0,0,3, 3.2, 0,0,0,-3:1,0,0,2,0,0,5,0,0)
ss <- as(sx, "sparseVector")
stopifnot(identical(ss,
   sparseVector(x = c(2, -1, -2, 3, 1, -3, 5, 3.2),
                i = c(15L, 10:9, 3L,12L,8L,18L, 4L), length = 20L)))

(ns <- sparseVector(i= c(7, 3, 2), length = 10))
stopifnot(identical(ns,
      new("nsparseVector", length = 10, i = c(2, 3, 7))))