Loop through array, convert strings to array, push to new array in Ruby

Question

I'm currently working on a project where I need to loop through an array of strings, convert those strings into arrays, and push those arrays into a larger array. Some of the strings have word duplication, so I need to remove that as well. I want to avoid hard-coding everything, so I'm trying to write as many functions as I can.

Here's an example of what I'm talking about.

old_array = ['Lilies are lovely lovely', 'Roses are romantic romantic', 'Daisies are bright bright']

new_array = []

Here's what the new array should look like:

new_array = [['Lilies', 'are', 'lovely'], ['Roses', 'are', 'romantic'], ['Daisies', 'are', 'bright']]

So the strings from old_array must be transformed into sub-arrays, with duplicate words removed.

I've been trying this and variations for a while, and it's not working very well.

def s_to_a(array)
  array.each do |string|
    string.split(" ").uniq
    new_array.push(string) #pretty sure this is incorrect
  end
end

s_to_a(old_array)

The error I keep getting is that new_array is an undefined local variable because I initialized it outside the function. Am I going about this the wrong way? Anyone have any pointers?

Answer 1

This sort of thing is easiest done with map , like so:

new_array = old_array.map{|s| s.split.uniq }

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Details

map is an Enumerable method that converts or "maps" the enumerable object it is called on (often an array ) into a new array . This is more convenient than manually pushing into sub-arrays with nil-checking.

The String method split by default splits on whitespace characters, so we can just call it without an argument and it will return an array of words. For a bit more detail... split uses $; as its default parameter, which is Ruby's global field separator variable... if the field separator is nil, which it is by default, split defaults to whitespace separation .