# sparseVector: Sparse Vector Construction from Nonzero Entries In Matrix: Sparse and Dense Matrix Classes and Methods

 sparseVector R Documentation

## 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)
```

### 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.

### Details

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

### Value

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

### Author(s)

Martin Maechler

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

### Examples

```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))))
```

Matrix documentation built on Nov. 11, 2022, 9:06 a.m.