# Ensure/collapse an array into n dimensions and restore the old dimensions

### Description

`nameNd`

ensures a given number of dimensions:
If `a`

has less than `N`

dimensions, new dimensions of length 1 are appended.
If `a`

has more than `N`

dimensions, the supernumerary dimensions are collapsed onto
the last dimension.

Attributes `old.dim`

and `old.dimnames`

are used by default. `restoredim`

is the
inverse of `makeNd`

.

### Usage

1 2 3 4 |

### Arguments

`a` |
an array (matrix, vector) |

`N` |
the desired number of dimensions, 0 to remove the |

`old` |
list containing a list with (possibly) elements |

`n` |
how many makeNdim steps to go back? |

`...` |
ignored |

`usedim` |
use only the specified dimensions |

`fromend` |
if |

`drop` |
should 1d arrays drop to vectors? |

### Details

Note that missing attributes as well as `old.dim = NULL`

produce a (dimensionless)
vector. This is also the case if `a`

lost the `old.*`

attributes during
computations like `as.numeric`

, `c`

, etc..

`fromend`

together with numeric `usedim`

specifies dimensions counting from the
end. E.g. `fromend = TRUE`

and `usedim = 1 : 3`

for an array to be restored to 10d
means restoring dimensions 8 : 10. `fromend = TRUE`

and `usedim = -(1 : 3)`

restores
dimensions 1 to 7.

### Value

N-dimensional array

an array

### Author(s)

Claudia Beleites

Claudia Beleites

### Examples

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 | ```
v <- arrayhelpers:::v
v
makeNd (v, 1)
dim (makeNd (v, 1))
dim (makeNd (v, 3))
m <- arrayhelpers:::m
m
makeNd (m, 1)
dim (makeNd (m, 1))
makeNd (m, 0)
dim (makeNd (m, 0))
makeNd (m, 3)
a <- arrayhelpers:::a
a
dim (makeNd (a, 1))
dim (makeNd (a, 0))
makeNd (a, 2)
makeNd (a, -2)
makeNd (a, -4)
makeNd (a, 3);
a <- array (1 : 24, 4 : 3)
a
restoredim (makeNd (a, 0))
x <- makeNd (a, 0)
attr (x, "old")
``` |

Want to suggest features or report bugs for rdrr.io? Use the GitHub issue tracker. Vote for new features on Trello.