One of the hardest issues I’ve had so far in the ‘Grokking Algorithms” book is understanding how to implement various sorts/sort types. Unfortunately the confusion was compounded when I tried to emulate the following code, that does a sort:

*NOTE: The example code in the book is from Python 2.7 [code language=”Python”] def selectionSort(arr): #Sorts an array newArr = [] for i in range(len(arr)): smallest = findSmallest(arr) newArr.append(arr.pop(smallest)) return newArr [/code]

The above code is supposed to take an array and sort it left to right in ascending order (1, 2, 3, 4).

however when I implemented/tried to translate the code to Ruby, the following resulted:

[code language=”Ruby”]

def selection_sort(arr) #sorts an array new_arr = [] arr.each do smallest = findsmallest(arr) #smallest is a Fixnum new_arr << (arr.pop(smallest)) end

[/code] -here’s the problem though… the .pop method in Ruby doesn’t work like the .pop method in Python. The .pop in Python is actually more comparable to .delete_at in Ruby, leading to the following (correct) code.

[code language=”Ruby”]

while arr.length > 0 do smallest = findsmallest(arr) new_arr << arr.delete_at(smallest) end

[/code]