## `stats::unzipCol` -- extract columns from a list of lists

#### Introduction

`stats::unzipCol``(list)` extracts the columns of a matrix structure encoded by a list of lists.

#### Call(s)

`stats::unzipCol(list)`

#### Parameters

`list` | - | a list of lists.

#### Returns

a sequence of lists to be regarded as columns.

#### Related Functions

`stats::col`, `stats::sample2list`, `stats::zipCol`

#### Details

- `stats::unzipCol` treats a list of lists like a list of rows of a `stats::sample` and extracts the columns. In conjunction with `stats::sample2list` it is useful for extracting the columns of a `stats::sample`.
- `stats::unzipCol` is the inverse of `stats::zipCol`.

#### Example 1

We extract the columns from a list of rows representing a matrix structure:

    >> stats::unzipCol([[a11, a12], [a21, a22], [a31, a32]])

                         [a11, a21, a31], [a12, a22, a32]

#### Example 2

A list of rows is used to create a sample:

    >> stats::sample([[123, s, 1/2], [442, s, -1/2], [322, p, -1/2]])

                                  123  s   1/2
                                  442  s  -1/2
                                  322  p  -1/2

We re-convert the sample to a list of lists:

    >> stats::sample2list(%)

                  [[123, s, 1/2], [442, s, -1/2], [322, p, -1/2]]

Finally, we extract the columns:

    >> stats::unzipCol(%)

                   [123, 442, 322], [s, s, p], [1/2, -1/2, -1/2]

#### Changes

- new function

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