placesvast.blogg.se

Group enumerable elements by the block return value. More Fascinating Methods MethodĮxactly what the name says, count things that evaluate to true inside a block I think this is genius, because it keeps a ‘sliding window’ sort of effect into our enumerable object, instead of having to mess around with array indexes. Then it yields a dup of the array if the array has the requested size. But then it adds the element to the array and it trims the array (using Array#shift) if the size is bigger than what we want. The implementation starts with an empty Ruby array, then it iterates through the elements using each.Įverything is pretty standard until here. You can find the original source code here. Note: This comes from the Rubinius implementation of Enumerable.

What I find even more fascinating is the implementation for the each_cons method. If you wanted to know how many times this pattern occurs, instead of getting a true / false result, you can just change any? to count. This method is really useful, you can use it to find n-grams or to check if a sequence of numbers is contiguous when combined with all?, another Enumerable method.Įach_cons gives you sub-arrays of size n, so if you have, then each_cons(2) will give you, ]. My new favorite Enumerable method is each_cons! There are over 20 Ruby Enumerable methods. Gives you a new array where every number has been doubled.Įxactly what happens depends on what method you use, map helps you transform all the values, select lets you filter a list & inject can be used to add up all the values inside an array. In that block you tell them what you want to do with every element. Enumerable is a collection of iteration methods, a Ruby module, and a big part of what makes Ruby a great programming language.Įnumerable includes helpful methods like:Įnumerable methods work by giving them a block.