Question

How to flatten a 2D array into a sorted one-dimensional array with unique values in Ruby

Answer 1

# Function that flattens a 2D array, sorts it, removes duplicates,
# and returns a new sorted array with unique values
def flatten_sort_unique(array2d)

  # 1. Flatten the 2D array into a 1D array
  flat = array2d.flatten

  # 2. Sort the flattened array
  flat.sort!

  # 3. Remove duplicates using uniq
  unique = flat.uniq

  unique
end

array2d = [
  [4, 3, 3, 2, 4],
  [30, 10, 10],
  [10, 30],
  [1, 1, 6, 7, 7, 7, 8],
]

arr = flatten_sort_unique(array2d)

# Print results
arr.each do |n|
  print "#{n}\t"
end


=begin
run

1   2   3   4   6   7   8   10   30

=end

 

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