How to Sort Everything in an Array Except Special Chars - Ruby

Question

I am trying to sort an array of letters alphabetically, but keep the special character in the same spot, in ruby.

For example,

word = ["f", "a", "s", "t", "-", "c", "a", "r", "s"]

How can I sort the whole thing alphabetically, but keep the "-" where it is. If I sort how it is now then the "-" will go to the front which I don't want. I have tried fifteen different ways, and I can't figure it out. Can you help?

@ToddA.Jacobs `"a", "a", "c", "f", "-", "r", "s", "s", "t"]` — anothernewbiecoder, Apr 26 '21 at 05:36
Oh! just realized something! Maybe I can add it by its original index? Iterate through the first array, find the index of the special char, go through the second array and use the insert method at the index? — anothernewbiecoder, Apr 26 '21 at 05:39
@anothernewbiecoder Yeah that will work. If you figure it out then post your answer (you are allowed to answer your own question). — Sagar Pandya, Apr 26 '21 at 05:56
@ToddA.Jacobs Got it to work, I guess all I had to do was post it on here lol — anothernewbiecoder, Apr 26 '21 at 06:11

score 1 · Answer 1 · answered Apr 26 '21 at 05:40

Some really verbose way to do this, to explain the logic around what you need to achieve. There's some 'cleaner' methods to achieve this, but I feel this gives more understanding.

Adding an additional special character to the array for better test coverage:

let(:input) { ["f", "a", "s", "t", "-", "c", "a", "r", "s", "/"] }
let(:desired_output) { ["a", "a", "c", "f", "-", "r", "s", "s", "t", "/"] }

it "takes the input and gives the desired output" do
  expect(sort_alphanumeric_characters(input)).to eq(desired_output)
end

Call .map and .select on the array to enumerate over the values and then call .with_index as you'll need to retain indicies for later.

def sort_alphanumeric_characters(word_as_array)
  # assuming you mean non-alphanumeric
  # collect those indicies which are 'special' characters
  # the regex matches the string with anything outside of the alphanumeric range. Note the '^'
  special_character_indicies = word_as_array.map.with_index { |val, indx| indx if val =~ /[^a-zA-Z0-9]/ }.compact
  # collect all characters by index that were not yielded as 'special'
  alphanumeric_array = word_as_array.select.with_index { |char, indx| char unless special_character_indicies.include? indx }
  # sort the alphanumeric array
  sorted_alphanumeric_array = alphanumeric_array.sort
  # use Array#insert to place the 'special' by index
  special_character_indicies.each do |special_indx|
    special_char = word_as_array[special_indx]
    sorted_alphanumeric_array.insert(special_indx, special_char)
  end
  # return desired output
  sorted_alphanumeric_array
end

And what are methods that can do it? I thought of a lot, and I feel like I am right there but I can't see it. I was thinking insert would be really helpful! — anothernewbiecoder, Apr 26 '21 at 05:47
Oh, I thought you were saying there was something in addition to that! — anothernewbiecoder, Apr 26 '21 at 06:05

anothernewbiecoder · Answer 2 · 2021-04-26T06:15:59.167

0

As soon as I posted I had a lightning bolt (love it when that happens). This is really not that great of a solution, but it did work!!

    def scramble_words(str)
      idx = 0 
      chars = str.delete("^a-z").chars
      first_ele = chars.shift
      last_ele = chars.pop
    
      str.chars.each_with_index {|c, i| idx = i if c =~ /[^a-z" "]/ }
    
      (first_ele + chars.sort.join  + last_ele).insert(idx, str[idx])
    
    end
    
    p scramble_words('card-carrying') == 'caac-dinrrryg'
    p scramble_words("shan't") == "sahn't"
    p scramble_words('-dcba') == '-dbca'

edited Apr 26 '21 at 06:15

answered Apr 26 '21 at 06:10

anothernewbiecoder

21
4

```scramble_words 'this-HAS-more-THAN-one-SPECIAL-character-AND-capslocks-WORDS' IndexError: index 59 out of string``` so you're removing a lot of characters with the regex and only really expecting one special character in that solution – benjessop Apr 26 '21 at 07:08
The first and last character are treated differently. If this is the actual output you expect, you should update your question accordingly. (also include those examples in your question) – Stefan Apr 26 '21 at 08:11
Oh yeah! I didn’t tell that part. The first and last letter stay in the same place and the special character. Then the middle scrambles. – anothernewbiecoder Apr 26 '21 at 15:32
The reason I didn’t add that part is because I knew that part. The part I was struggling with was keeping the special character there and sorting everything else. I showed the whole problem but I can change it? – anothernewbiecoder Apr 26 '21 at 15:34
@benjessop that is right! I didn't think of that at first, and then I ran into a test case that had multiple special characters and had a major facepalm moment. I ended switching this to a hash. So, I iterated over the string putting all special characters into a hash. Then at the end I inserted them. – anothernewbiecoder Apr 27 '21 at 20:30

How to Sort Everything in an Array Except Special Chars - Ruby

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