# as.pairwise

##### Convert a results matrix to a board

Given a square matrix giving the results of pairwise comparisons, return a board object whose rows show the results of the comparisons.

- Keywords
- math

##### Usage

`as.pairwise(x)`

##### Arguments

- x
- A square matrix

##### Details

With `x`

an $n$-by-$n$ square matrix, the rows and
columns each correspond to one of $n$ “competitors”. The
$(i,j)$-th entry the number of times competitor $i$ beats
competitor $j$ (the leading diagonal holds `NA`

s because a
competitor can't play himself).

Function `as.pairwise()`

turns this into a
$n(n-1)/2$-by-$n$ matrix whose rows each correspond to a
pairwise comparison. Any row has exactly two non-`NA`

entries,
in columns $i$ and $j$, that correspond to elements
$(i,j)$ and $(j,i)$ of `x`

. Thus the entry in column
$i$ is the number of times competitor $i$ beats competitor
$j$; and the entry in column $j$ is the number of times
competitor $j$ beats competitor $i$.

##### See Also

##### Examples

```
a <- matrix(rpois(25,4),5,5)
rownames(a) <- letters[1:5]
colnames(a) <- letters[1:5]
as.pairwise(a)
```

*Documentation reproduced from package aylmer, version 1.0-11, License: GPL-2*