Split a string into a single element array in ruby

Question

So I wrote this code:

def translate_word word
    vowel = ["a", "e", "i", "o", "u"]
    if vowel.include? word[0] 
        word = word + "ay"
    elsif vowel.include? word[1]
        word = word[1..-1] + word[0] + "ay"
    else
        word = word[2..-1] + word[0..1] + "ay"
    end
end

Translates a word into pig latin. For my purposes, works great. But what if we want to translate more than one word?

def translate string 
   vowel = ["a", "e", "i", "o", "u"]
   words = string.split(" ")
   words.each do |word|
     if vowel.include? word[0] 
         word = word + "ay"
     elsif vowel.include? word[1]
         word = word[1..-1] + word[0] + "ay"
     else
         word = word[2..-1] + word[0..1] + "ay"
     end
   end
   words.join(" ")
end

Except, if we try to do this with one word, it'll notice there aren't any spaces, say screw that, and return a string. Won't even throw me an error when I try to .each it, but the .each won't do any thing.

puts "apple".split

#=>apple

puts translate "apple"

#=>apple

This isn't an insurmountable problem. I could just run string.includes? " " and then run the two slightly different programs depending on if it was there or not. But this seems very ineloquent. What would be a better or more idiomatic way to deal with the string and the loop?

Stefan · Accepted Answer · 2014-09-17 13:29:21Z

3

Assigning another value to the block argument doesn't change the array element:

words.each do |word|
  word = word + "ay" # <- this doesn't work as expected
end

To change the element, you have to call a method that changes the receiver, e.g.:

words.each do |word|
  word << "ay"
end

However, instead of repeating the algorithm, you could just call translate_word for each word:

def translate(string)
  string.split.map { |word| translate_word(word) }.join(" ")
end

translate("apple orange")
#=> "appleay orangeay"

I've used split and join here, but you could also use gsub:

def translate(string)
  string.gsub(/\w+/) { |word| translate_word(word) }
end

edited Sep 17, 2014 at 13:29

answered Sep 17, 2014 at 13:17

Stefan

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Comments

Stefan Große · Accepted Answer · 2014-09-17 13:11:38Z

1

As far as I can see you're not manipulating your original array words.

You would need something like this:

def translate string 
   vowel = ["a", "e", "i", "o", "u"]
   words = string.split(" ")
   words.each_with_index do |word, index|
     if vowel.include? word[0] 
         word = word + "ay"
     elsif vowel.include? word[1]
         word = word[1..-1] + word[0] + "ay"
     else
         word = word[2..-1] + word[0..1] + "ay"
     end
     words[index] = word
   end
   words.join(" ")
end

answered Sep 17, 2014 at 13:11

Stefan Große

536 bronze badges

5 Comments

Roman Davis Over a year ago

I don't get it. Didn't I change the value that word points to? And isn't a list just a bunch of pointers? Or am I making some sort of fundamental misunderstanding?

Stefan Große Over a year ago

In the each loop, each value of self is written into a new variable. In your case every value of words is written into a new variable word. If you modify word, that doesn't mean you modified self aka. words.

Roman Davis Over a year ago

That is extremely unintuitive to me. Thanks for telling me.

Stefan Große Over a year ago

No problem. There is also a difference betweeen map and map!. While map also creates a new object, map! really changes the current object. With map! there is no need to reassign the object created. e.g. words.map!{ |word| translate_word(word) } does the same like words = words.map{ |word| translate_word(word) }

Roman Davis Over a year ago

I knew about the "!" on a lot of variables. The distinction was biting me with .capitalize vs .capitalize! I didn't expect it to apply to iterators. What about .each? Could I .each! and get more permanent affect on my list somehow?

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