k_fold-methods {DelayedTensor} | R Documentation

## k-mode Folding of 2D DelayedArray

### Description

k-mode folding of a matrix into a Tensor. This is the inverse funtion to `k_unfold` in the m mode. In particular, `k_fold(k_unfold(darr, m), m, dim(darr))` will result in the original Tensor.

### Usage

    k_fold(mat, m = NULL, modes = NULL)

    ## S4 method for signature 'DelayedArray'
    k_fold(mat, m, modes)

### Arguments

`mat` | DelayedArray object (only 2D)
`m` | the index of the mode that is mapped onto the row indices
`modes` | the modes of the output DelayedArray

### Details

This function is an extension of the `k_fold` by DelayedArray.

This is a wrapper function to `fold`.

### Value

DelayedArray object with modes given by `modes`

### References

T. Kolda, B. Bader, "Tensor decomposition and applications". SIAM Applied Mathematics and Applications 2009.

### See Also

`fold`, `k_unfold`

### Examples

    library("DelayedRandomArray")
    darr <- RandomUnifArray(c(2,3,4))
    matT2 <- k_unfold(darr, m=2)
    identical(
        as.array(k_fold(matT2, m=2, modes=c(2,3,4))),
        as.array(darr))

[Package DelayedTensor version 1.0.0 Index]