Data.Grid.Internal.Convolution

Documentation

autoConvolute

Arguments

:: (Dimensions dims, Dimensions window, Functor f, Neighboring window)

=> (Grid window (Coord dims) -> f (Coord dims))

Restrict out of bounds coordinates in some way. Use clampWindow, wrapWindow or safeWindow

-> (f a -> b)

Collapse the context down to a value

-> Grid dims a

Starting grid

-> Grid dims b

Perform a computation based on the context surrounding a cell Good for doing things like Linear Image Filters (e.g. gaussian blur) or simulating Cellular Automata (e.g. Conway's game of life)

This function accepts a function which indicates what to do with 'out-of-bounds' indexes, clampWindow, wrapWindow and safeWindow are examples.

It also acccepts a transformation function which operates over the functor created by the first parameter and collapses it down to a new value for the cell at that position.

This function is best used with Type Applications to denote the desired window size; the Grid passed to the given function contains the current cell (in the middle) and all the surrounding cells.

Here's an example of computing the average of all neighboring cells, repeating values at the edge of the grid when indexes are out of bounds (using clampWindow)

gaussian :: (Dimensions dims) => Grid dims Double -> Grid dims Double
gaussian = autoConvolute clampBounds avg
 where
  avg :: Grid '[3, 3] Double -> Double
  avg g = sum g / fromIntegral (length g)

convolute

Arguments

:: (Functor f, Dimensions dims)

=> (Coord dims -> f (Coord dims))

Build a neighboring context within a functor from the current coord

-> (f a -> b)

Collapse the context to a single value

-> Grid dims a

Starting grid

-> Grid dims b

This is a fully generic version of autoConvolute which allows the user to provide a function which builds a context from the current coord, then provides a collapsing function over the same functor.

clampBounds :: (Dimensions dims, Functor f) => f (Coord dims) -> f (Coord dims)

Use with autoConvolute; Clamp out-of-bounds coordinates to the nearest in-bounds coord.

wrapBounds :: (Dimensions dims, Functor f) => f (Coord dims) -> f (Coord dims)

Use with autoConvolute; Wrap out-of-bounds coordinates pac-man style to the other side of the grid

omitBounds :: (Dimensions dims, Functor f) => f (Coord dims) -> Compose f Maybe (Coord dims)

Use with autoConvolute; Out of bounds coords become Nothing

window :: forall window dims. (Neighboring window, Dimensions window) => Coord dims -> Grid window (Coord dims)

Given a coordinate generate a grid of size window filled with coordinates surrounding the given coord. Mostly used internally

class Neighboring dims

Minimal complete definition

neighborCoords

Instances

(KnownNat n, Neighboring ns) => Neighboring (n ': ns)

Defined in Data.Grid.Internal.Convolution

Methods

neighborCoords :: Grid (n ': ns) (Coord (n ': ns))

KnownNat n => Neighboring (n ': ([] :: [Nat]))

Defined in Data.Grid.Internal.Convolution

Methods

neighborCoords :: Grid (n ': []) (Coord (n ': []))