Safe Haskell | None |
---|---|

Language | Haskell2010 |

## Synopsis

- rearrangeShape :: [Int] -> [a] -> [a]
- rearrangeInverse :: [Int] -> [Int]
- rearrangeReach :: [Int] -> Int
- rearrangeCompose :: [Int] -> [Int] -> [Int]
- isPermutationOf :: Eq a => [a] -> [a] -> Maybe [Int]
- transposeIndex :: Int -> Int -> [a] -> [a]
- isMapTranspose :: [Int] -> Maybe (Int, Int, Int)

# Documentation

rearrangeShape :: [Int] -> [a] -> [a] Source #

Calculate the given permutation of the list. It is an error if the permutation goes out of bounds.

rearrangeInverse :: [Int] -> [Int] Source #

Produce the inverse permutation.

rearrangeReach :: [Int] -> Int Source #

Return the first dimension not affected by the permutation. For
example, the permutation `[1,0,2]`

would return `2`

.

rearrangeCompose :: [Int] -> [Int] -> [Int] Source #

Compose two permutations, with the second given permutation being applied first.

isPermutationOf :: Eq a => [a] -> [a] -> Maybe [Int] Source #

Check whether the first list is a permutation of the second, and if so, return the permutation. This will also find identity permutations (i.e. the lists are the same) The implementation is naive and slow.

transposeIndex :: Int -> Int -> [a] -> [a] Source #

If `l`

is an index into the array `a`

, then ```
transposeIndex k n
l
```

is an index to the same element in the array ```
transposeArray k n
a
```

.

isMapTranspose :: [Int] -> Maybe (Int, Int, Int) Source #

If `perm`

is conceptually a map of a transposition,
`isMapTranspose perm`

returns the number of dimensions being mapped
and the number dimension being transposed. For example, we can
consider the permutation `[0,1,4,5,2,3]`

as a map of a transpose,
by considering dimensions `[0,1]`

, `[4,5]`

, and `[2,3]`

as single
dimensions each.

If the input is not a valid permutation, then the result is undefined.