In my version of Selection Sort in Ruby, I start with the first object in the array and compare it to the next one and so on until I find lowest value, swapping it with the first objects position. I then repeat that on the second object, and the next, until the whole list is sorted.
Here’s an animated sequence of Selection Sort that I found on the Selection Sort Wikipedia.
As always, start with the tests.
require 'test/unit'
require "./selection_sort.rb"
class SortingTests < Test::Unit::TestCase
def test_selection_sort
@unsorted = (0..1000).to_a.shuffle
@sorted = @unsorted.sort
selection_sort = SelectionSort.new
result = selection_sort.sort(@unsorted)
assert_equal @sorted, result
end
endAnd next, the Selection Sort function.
class SelectionSort
def sort(to_sort)
arr_to_sort = to_sort
length_of_sort = arr_to_sort.length
position_in_array = 0
while position_in_array < length_of_sort
@min_val = arr_to_sort[position_in_array]
(length_of_sort - position_in_array).times.each do |i|
if arr_to_sort[position_in_array + i] < @min_val
@min_val = arr_to_sort[position_in_array + i]
@min_val_index = position_in_array + i
end
end
if @min_val < arr_to_sort[position_in_array]
@swap_value = arr_to_sort[position_in_array]
arr_to_sort.delete_at(@min_val_index)
arr_to_sort.insert(position_in_array, @min_val)
arr_to_sort.delete_at(position_in_array+1)
arr_to_sort.insert(@min_val_index, @swap_value)
end
position_in_array += 1
end
return arr_to_sort
end
end