Menu
I have a list of elements (e.g. numbers) and I want to retrieve a list of all possible pairs. How can I do that using Ruby?
Example:
l1 = [1, 2, 3, 4, 5]
Result:
l2 #=> [[1,2], [1,3], [1,4], [1,5], [2,3], [2,4], [2,5], [3,4], [3,5], [4,5]]
539
Ruby | Array combination() operation Array#combination() : combination() is an Array class method which invokes with a block yielding all combinations of length 'n' of elements of the array. Syntax: Array.
Ruby | Array class first() function first() is a Array class method which returns the first element of the array or the first 'n' elements from the array.
The find method locates and returns the first element in the array that matches a condition you specify. find executes the block you provide for each element in the array. If the last expression in the block evaluates to true , the find method returns the value and stops iterating.
exclude? is defined as ! include?, meaning it is the exact opposite of include? . See the source. This means that it works for Arrays and Hashes too, as well as for Strings.
In Ruby 1.8.6, you can use Facets:
require 'facets/array/combination'
i1 = [1,2,3,4,5]
i2 = []
i1.combination(2).to_a # => [[1, 2], [1, 3], [1, 4], [1, 5], [2, 3], [2, 4], [2, 5], [3, 4], [3, 5], [4, 5]]
In 1.8.7 and later, combination is built-in:
i1 = [1,2,3,4,5]
i2 = i1.combination(2).to_a
Or, if you really want a non-library answer:
i1 = [1,2,3,4,5]
i2 = (0...(i1.size-1)).inject([]) {|pairs,x| pairs += ((x+1)...i1.size).map {|y| [i1[x],i1[y]]}}
If you love us? You can donate to us via Paypal or buy me a coffee so we can maintain and grow! Thank you!
Donate Us With
