CODEWITHSUNDEEP
rubyarraysset
Max Rhan
Max Rhan

Reputation: 345

Convert arrays of array to set of arrays

I have an array of arrays and want to filter all arrays which have the same elements, which might only differ in their order.

[[1,0,1],[1,1,0],[2,3,5]] => [[1,0,1],[2,3,5]]

or similiar. Maybe I should use the Set class for this? But maybe this can also be achieved with another method?

Upvotes: 2

Views: 1033

Answers (4)

tokland
tokland

Reputation: 67900

At this moment all the answers use O(n log n) sort as uniqueness function. A histogram (frequency counter) is O(n):

require 'facets/enumerable/frequency'
xss = [[1, 0, 1], [1, 1, 0], [2, 3, 5]]
xss.uniq(&:frequency)
#=> [[1, 0, 1], [2, 3, 5]]

Note however, that sort is a core optimized method and overall it will probably perform better.

Upvotes: 2

SwiftMango
SwiftMango

Reputation: 15294

[[1,0,1],[1,1,0],[2,3,5]].uniq{|i| i.sort}

or

[[1,0,1],[1,1,0],[2,3,5]].uniq(&:sort)

Output:

[[1, 0, 1], [2, 3, 5]]

sort will make sure all sub-arrays are in the same order, and uniq gets rid of redundant items.

Upvotes: 10

siame
siame

Reputation: 8657

require 'set'

a = [[1,0,1],[1,1,0],[2,3,5]]

set = Set.new

a.map {|x| set << x.sort}
b = set.to_a

=> [[0, 1, 1], [2, 3, 5]]

Upvotes: 0

Reck
Reck

Reputation: 8792

This should do it.

require 'set'

set = Set.new
set << [1,0,1].sort
set << [1,1,0].sort
set << [2,3,5].sort

set.each do |e|
  puts e.to_s
end

Upvotes: 2

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