At

Extensions

At

XLua ť Extensions ť Static Array

number array:at ( number i1, i2, ... in )

Returns the value at the calculated n-dimensional index given by i1, i2, ... in. The number of indexes must match the dimensionality originally specified in array.new() or the last call to resize(). There is no bounds checking provided on the individual indexes. The value parameter must be the last parameter, after the variable number of index parameters.

Given dimensions of size d₁, d₂, ... d_n, and indexes i₁, i₂, ... i_n, then the index is calculated as:
idx = [(d₂ * d₃ * ... * d_n) * i₁] + [(d₃ * d₄ * ... * d_n) * i₂] + ... + (d_n * i_n-1) + i_n

For a 3-dimensional array then, the calculated index would be:
idx = [(d₂ * d₃) * i₁] + (d₃ * i₂) + i₃

Parameters

in One or more array indexes matching the dimensionality of the array

Return Values

number Value at the calculated index

Example

-- Assume we have a 3-dimensional array "arr"

local val = arr:at(1, 2, 3)

-- If the array was created with dimensions 4, 5, 6

-- then the following value should be the same.

local idx = (5 * 6 * 1) + (6 * 2) + 3

local val2 = arr[idx]

assert(val == val2)

Copyright 2010 Justin Aquadro