http://apidock.com/rails/Enumerable/group_by#508-Array-clustering
Sometimes you don’t want to mangle sequence of an array and just want to group adjacent values. Here’s a nice method to do so (drop it in your initializers directory or something):
module Enumerable
# clumps adjacent elements together
# >> [2,2,2,3,3,4,2,2,1].cluster{|x| x}
# => [[2, 2, 2], [3, 3], [4], [2, 2], [1]]
def cluster
cluster = []
each do |element|
if cluster.last && yield(cluster.last.last) == yield(element)
cluster.last << element
else
cluster << [element]
end
end
cluster
end
end
Similarly you can do the clustering on more complex items. For instance you want to cluster Documents on creation date and their type:
Document.all.cluster{|document| [document.created_on, document.type]}