CODEWITHSUNDEEP
rubyrecursionproc
Peter Nolan
Peter Nolan

Reputation: 1

Proc-tition method, issue with what should be a simple if conditional

I'm to write a method in Ruby that partitions an array based on a proc, both passed in the arguments. Here is my full method:

def proctition(arr, &prc)
    failed = []
    passed = []
    debugger
    if arr != arr.flatten
        passed.push(*arr[0])
        arr[1].each_with_index do |ele, i|
            if prc.call(ele)
                passed.push(ele)
                remainder = arr[1].pop(arr.size - i + 1)
                self.proctition([passed, remainder], &prc)
            else
                failed.push(ele)
                remainder = arr[1].pop(arr.size - i + 1)
                self.proctition([passed, remainder], &prc)
            end
        end
    else
        [*passed, *failed]
    end
end

As far as I know there's no method that selectively both removes an element from an array and evaluates to those removed elements like pop() does for the last default 1 or however many digits you specify. I was able to figure out how to use recursion to my advantage in a previous method and I feel the solution is along this track. My strategy was to populate passed and failed arrays that maintain their scope through each level of recursion, with my recursive call to my method passing a 2D array, I then added what I thought would be a simple check at the beginning whether or not an array is 2D or not arr != arr.flatten and I have run this exact statement through pry during the runtime of this program, and gotten what I expected this statement to evaluate to in the original method call: false, which is to say that this array is the same as the array when you 'flatten' it by a call to the method by the same name. And then within this if block I do the sorting and pruning and the recursive call on the pruned array. However, in actual execution it must be evaluating to the opposite as it goes right to the else block to return an empty concatenation of arrays.

Upvotes: -1

Views: 74

Answers (1)

Chris
Chris

Reputation: 36620

It's unclear why you're iterating over your array while trying to modify it and trying to use recursion. It appears a very overthought and overcomplicated solution for a very straightforward problem.

def proctition(arr, &prc)
  good, bad = [], []
  arr.each do |x| 
    if prc.call(x)
      good << x 
    else 
      bad << x 
    end 
  end
  [*good, *bad]
end

And now:

irb(main):012:0> proctition([1, 2, 3, 4], &:even?)
=> [2, 4, 1, 3]

Upvotes: 1

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