Skip to content

Instantly share code, notes, and snippets.

@rm-code rm-code/ArrayRotation.lua
Last active Aug 7, 2018

Embed
What would you like to do?
Helper module which allows the rotation of square and non square arrays.
--==================================================================================
-- Copyright (C) 2017 by Robert Machmer =
-- =
-- Permission is hereby granted, free of charge, to any person obtaining a copy =
-- of this software and associated documentation files (the "Software"), to deal =
-- in the Software without restriction, including without limitation the rights =
-- to use, copy, modify, merge, publish, distribute, sublicense, and/or sell =
-- copies of the Software, and to permit persons to whom the Software is =
-- furnished to do so, subject to the following conditions: =
-- =
-- The above copyright notice and this permission notice shall be included in =
-- all copies or substantial portions of the Software. =
-- =
-- THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR =
-- IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, =
-- FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE =
-- AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER =
-- LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, =
-- OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN =
-- THE SOFTWARE. =
--==================================================================================
local ArrayRotation= {
_VERSION = "1.0.0",
_DESCRIPTION = "Rotation of arrays in 90° increments." ,
_URL = 'https://gist.github.com/rm-code/4118d4a97d8cde16952199d94b84ead0',
}
-- ------------------------------------------------
-- Private Functions
-- ------------------------------------------------
---
-- Rotates a two dimensional array by 90°.
-- @tparam table arr The array to rotate.
-- @treturn table The rotated array.
--
local function rotate90( arr )
local rotatedArray = {}
for x = 1, #arr do
for y = 1, #arr[x] do
local r, c = #arr-(x-1), y
rotatedArray[c] = rotatedArray[c] or {}
rotatedArray[c][r] = arr[x][y]
end
end
return rotatedArray
end
---
-- Rotates a two dimensional array by 180°.
-- @tparam table arr The array to rotate.
-- @treturn table The rotated array.
--
local function rotate180( arr )
local rotatedArray = {}
for x = 1, #arr do
for y = 1, #arr[x] do
local r, c = #arr-(x-1), #arr[x]-(y-1)
rotatedArray[r] = rotatedArray[r] or {}
rotatedArray[r][c] = arr[x][y]
end
end
return rotatedArray
end
---
-- Rotates a two dimensional array by 270°.
-- @tparam table arr The array to rotate.
-- @treturn table The rotated array.
--
local function rotate270( arr )
local rotatedArray = {}
for x = 1, #arr do
for y = 1, #arr[x] do
local r, c = x, #arr[x]-(y-1)
rotatedArray[c] = rotatedArray[c] or {}
rotatedArray[c][r] = arr[x][y]
end
end
return rotatedArray
end
-- ------------------------------------------------
-- Public Functions
-- ------------------------------------------------
---
-- Rotates a two dimensional array.
-- @tparam table arr The array to rotate.
-- @tparam number steps The amount of rotation to apply (0=0°, 1=90°, 2=180°, 3=270°)
-- @treturn table The rotated array.
--
function ArrayRotation.rotate( arr, steps )
if steps == 0 then
return arr
elseif steps == 1 then
return rotate90( arr )
elseif steps == 2 then
return rotate180( arr )
elseif steps == 3 then
return rotate270( arr )
end
end
return ArrayRotation
local ArrayRotation = require( 'ArrayRotation' )
local foo = {
{ 1, 2, 3 },
{ 3, 4, 5 },
{ 6, 7, 8 },
}
local bar = {
{ 'a', 'b', 'c', 'd', 'e', 'f' },
{ 'g', 'h', 'i', 'j', 'k', 'l' },
{ 'm', 'n', 'o', 'p', 'q', 'r' },
}
local function dump( array )
local str = ''
for r = 1, #array do
for c = 1, #array[r] do
str = str .. ' ' .. array[r][c]
end
str = str .. '\n'
end
print( str )
end
dump( foo )
dump(ArrayRotation.rotate( foo, 1 ))
dump(ArrayRotation.rotate( foo, 2 ))
dump(ArrayRotation.rotate( foo, 3 ))
dump( bar )
dump(ArrayRotation.rotate( bar, 1 ))
dump(ArrayRotation.rotate( bar, 2 ))
dump(ArrayRotation.rotate( bar, 3 ))
Sign up for free to join this conversation on GitHub. Already have an account? Sign in to comment
You can’t perform that action at this time.