Lua - Slicing Arrays

In Lua, we do not have direct support for slicing array. But using table.unpack() method, we can achieve the same using following syntax:

Syntax

slicedArray = {table.unpack(array, startIndex, endIndex)}

Where

• array− source array.

• startIndex− index of array from where slicing is to be done.

• endIndex− index of array where slicing ends.

Example - Slicing array of characters

Create a new source file named main.lua and paste the following code to slice an array.

main.lua

-- source array
array = {"a", "b", "c", "d", "e", "f"}
-- unpack the array with start/end indexes
slicedArray = {table.unpack(array, 2, 4)}

-- iterate the sliced array and print the values
for key, value in pairs(slicedArray) do
    print(key, value)
end

Output

1	b
2	c
3	d

Example - Slicing array of numbers

Update the source file named main.lua and paste the following code to slice an array.

main.lua

-- source array
array = {1, 2, 3, 4, 5, 6}
-- unpack the array with start/end indexes
slicedArray = {table.unpack(array, 2, 4)}

-- iterate the sliced array and print the values
for key, value in pairs(slicedArray) do
    print(key, value)
end

Output

1	2
2	3
3	4

Example - Slicing array Using custom method

We can create a custom method, to get a sliced array.

Update the source file named main.lua and paste the following code to slice an array.

main.lua

-- custom function to get sliced array
function slice(array, first, last, step)
   local slicedArray = {}

   -- iterate the loop from first to loop
   -- fill the sliced array
   for i = first or 1, last or #array, step or 1 do
      slicedArray[#slicedArray+1] = array[i]
   end
   -- return the array
   return slicedArray
end

-- source array
sourceArray = {1, 2, 3, 4, 5, 6}
-- get sliced array
targetArray = slice(sourceArray, 2, 4)

-- iterate the sliced array and print values
for key, value in pairs(targetArray) do
    print(key, value)
end

Output

1	2
2	3
3	4