R: Retrieve or set a list of array element values

entry.value {geometry} | R Documentation

## Retrieve or set a list of array element values

### Description

`entry.value` retrieves or sets the values in an array `a` at the positions indicated by the rows of a matrix `idx`.

### Usage

    entry.value(a, idx)

### Arguments

`a` | An array.
`idx` | Numerical matrix with the same number of columns as the number of dimensions of `a`. Each row indices a cell in `a` of which the value is to be retrieved or set.
`value` | An array of length `nrow(idx)`.

### Value

`entry.value(a,idx)` returns a vector of values at the indicated cells. `entry.value(a,idx) <- val` changes the indicated cells of `a` to `val`.

### Author(s)

Raoul Grasman

### Examples

    a = array(1:(4^4),c(4,4,4,4))
    entry.value(a,cbind(1:4,1:4,1:4,1:4))
    entry.value(a,cbind(1:4,1:4,1:4,1:4)) <- 0

    entry.value(a, as.matrix(expand.grid(1:4,1:4,1:4,1:4)))
         # same as `c(a[1:4,1:4,1:4,1:4])' which is same as `c(a)'

[Package geometry version 0.4.0 Index]