Parsing one large array into several sub-arrays - ruby

Question

I have a list of adjectives (found here), that I would like to be the basis for a "random_adjective(category)" method.
I'm really just taking a stab at this, as my first real attempt at a useful program.
Step 1: Open file, remove formatting. No problem.
list=File.read('adjectivelist')
list.gsub(/\n/, " ")
The next step is to break the string up by category..
list.split(" ")
Now I have an array of every word in the file. Neat. The ones with a tilde before them represent the category names.
Now I would like to break up this LARGE array into several smaller ones, based on category.
I need help with the syntax here, although the pseudocode for this would be something like
Scan the array for an element which begins with a tilde.
Now create a new array based on the name of that element sans the tilde, and ALSO place this "category name" into the "categories" array. Now pull all the elements from the main array, and pop them into the sub-array, until you meet another tilde. Then repeat the process until there are no more elements in the array.
Finally I would pull a random word from the category named in the parameter. If there was no category name matching the parameter, it would return false and exit (this is simply in case I want to add more categories later.)
Tips would be appreciated

Answer 1

You may want to go back and split first time around like this:
categories = list.split(" ~")
Then each list item will start with the category name. This will save you having to go back through your data structure as you suggest. Consider that a tip: sometimes it's better to re-think the start of a coding problem than to head inexorably forwards
The structure you are reaching towards is probably a Hash, where the keys are category names, and the values are arrays of all the matching adjectives. It might look like this:
{
'category' => [ 'word1', 'word2', 'word3' ]
}
So you might do this:
words_in_category = Hash.new
categories.each do |category_string|
cat_name, *words = category_string.split(" ")
words_in_category[cat_name] = words
end
Finally, to pick a random element from an array, Ruby provides a very useful method sample, so you can just do this
words_in_category[ chosen_category ].sample
. . . assuming chosen_category contains the string name of an actual category. I'll leave it to you to figure out how to put this all together and handle errors, bad input etc

Answer 2

Use slice_before:
categories = list.split(" ").slice_before(/~\w+/)
This will create an sub array for each word starting with ~, containing all words before the next matching word.

Answer 3

If this file format is your original and you have freedom to change it, then I recommend you save the data as yaml or json format and read it when needed. There are libraries to do this. That is all. No worry about the mess. Don't spend time reinventing the wheel.