尝试删除数组中的元素：Ruby

Question

I'm working on a Codewar challenge in Ruby to remove elements from a array of strings. So far I have tried using the Array.delete_at(Array.index(value)) which is meant to remove the first occurrence of a repeating value from the array however that did not work. I believe I may need to combine that with something else but not sure what.

these are what my tests currently look like when I run them:

Expected: ["Hello", "Hello Again"], instead got: ["Hello"]
Expected: [1, 3, 5, 7, 9], instead got: [1]
Test Passed: Value == [[1, 2]]
Test Passed: Value == [["Goodbye"]]
Test Passed: Value == []

so far I'm using the .shift method, and that seems to have done half the job. any suggestions on how I can target the whole substring.

def remove_every_other(arr)
  arr.shift(1) 
end

for more clarification please find the practise tests and link to the Kata below: https://www.codewars.com/kata/5769b3802ae6f8e4890009d2/train/ruby

Test.describe("Basic tests") do
  Test.assert_equals(remove_every_other(['Hello', 'Goodbye', 'Hello Again']),['Hello', 'Hello Again'])
  Test.assert_equals(remove_every_other([1, 2, 3, 4, 5, 6, 7, 8, 9, 10]),[1, 3, 5, 7, 9])
  Test.assert_equals(remove_every_other([[1, 2]]), [[1, 2]])
  Test.assert_equals(remove_every_other([['Goodbye'], {'Great': 'Job'}]), [['Goodbye']])
  Test.assert_equals(remove_every_other([]), [])
end

Answer 1

There's a ton of tools in Enumerable that make this trivial:

a = %w[ a b c d e f ]

a.each_slice(2).map(&:first)
# => ["a", "c", "e"]

Where that first carves up the array into pairs, then takes the first of each pair.

The problem with your shift approach is it does one operation, it doesn't iterate. You must work through the whole array to make this happen.

Now you could use a combination of shift and an accumulator, but it's generally bad form to consume the array you're given when a more functional version exists. each_slice produces a new result, it doesn't alter the original, making it easier to coordinate in more complex code where that input value might be shared.

Answer 2

multiple solutions possible. But - don't forget that you do not need to remove elements to solve this challenge - your method needs to return proper values that's all. So following code should also work:

   arr.select{ |e| arr.find_index(e).even? }