Question

Anyone who can help me make this work?

array.each_with_index do |buffer,index|

    if array[index][8] == array[1..7][8]
      puts "match found"
    end
end

I want to compare if there is any doublets, but how do i define the search range to be my array index value from 1 to 7 except the index?

just to make it clear i want to compare array[1][8],[2][8],[3][8] and so on except [index][8]

Thanks 4 ur help…

Answer 1

You could use group_by to create groups of any doublets:

array.group_by {|v| v[8] }

This’ll give you a hash of {"group key" => ["group", "members"]}.

To get a list of all doublets, just select the groups that have more than one member:

array.group_by {|v| v[8] }.values.select {|g| g.length > 1 }

Furthermore, to eliminate any doublets from the list:

array.group_by {|v| v[8] }.values.map(&:first)

This will return a new array with any doublets eliminated, so that only the first item in any given doublet is returned.

array = [
  %w(1 2 3 4 5 6 7 8 9),
  %w(1 2 3 4 5 6 7 8 9),
  %w(a b d e f g h i j),
  %w(a b d e f g h i j),
  %w(j k l m n o p q r)
]

pp array.group_by {|v| v[8] }.values.map(&:first)

# Output:
# [["1", "2", "3", "4", "5", "6", "7", "8", "9"],
# ["a", "b", "d", "e", "f", "g", "h", "i", "j"],
# ["j", "k", "l", "m", "n", "o", "p", "q", "r"]]