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I need a collection that is like a set. Basically I'm scanning a long string and adding words to the collection but I want to be able to detect when there are duplicates.
If sets aren't available, what's the most efficient way of doing this in Ruby? Brownie points for example code.
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What is a Ruby set? A set is a class that stores items like an array… But with some special attributes that make it 10x faster in specific situations!
A Quick Intro to Ruby's Set (3 Part Series) All objects in a Set are guaranteed unique. Objects in a Set are not ordered. Sets are built on top of Hashes for super-fast object lookup.
%w(foo bar) is a shortcut for ["foo", "bar"] . Meaning it's a notation to write an array of strings separated by spaces instead of commas and without quotes around them. You can find a list of ways of writing literals in zenspider's quickref.
unshift will add a new item to the beginning of an array. With insert you can add a new element to an array at any position.
There is a Set class in ruby. You can use it like so:
require 'set' set = Set.new string = "a very very long string" string.scan(/\w+/).each do |word| unless set.add?( word ) # logic here for the duplicates end end Although, I'm wondering if you would want to count the instances in that case the following example would be better:
instances = Hash.new { |h, k| h[k] = 0 } string.scan(/\w+/).each do |word| instances[word] += 1 end From the documentation:
a = [ "a", "a", "b", "b", "c" ] a.uniq #gets you ["a", "b", "c"] a.uniq.uniq! #gets you nil (no duplicates :) If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
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