Unique In Order

Unique In Order

Implement the function unique_in_order which takes as argument a sequence and returns a list of items without any elements with the same value next to each other and preserving the original order of elements.

For example:

uniqueInOrder("AAAABBBCCDAABBB") == {'A', 'B', 'C', 'D', 'A', 'B'}
uniqueInOrder("ABBCcAD")         == {'A', 'B', 'C', 'c', 'A', 'D'}
uniqueInOrder([1,2,2,3,3])       == {1,2,3}

uniqueInOrder('AAAABBBCCDAABBB') == ['A', 'B', 'C', 'D', 'A', 'B']
uniqueInOrder('ABBCcAD')         == ['A', 'B', 'C', 'c', 'A', 'D']
uniqueInOrder([1,2,2,3,3])       == [1,2,3]

unique_in_order('AAAABBBCCDAABBB') == ['A', 'B', 'C', 'D', 'A', 'B']
unique_in_order('ABBCcAD')         == ['A', 'B', 'C', 'c', 'A', 'D']
unique_in_order([1,2,2,3,3])       == [1,2,3]

unique_in_order('AAAABBBCCDAABBB') == ['A', 'B', 'C', 'D', 'A', 'B']
unique_in_order('ABBCcAD')         == ['A', 'B', 'C', 'c', 'A', 'D']
unique_in_order([1,2,2,3,3])       == [1,2,3]

uniqueInOrder "AAAABBBCCDAABBB" == "ABCDAB"
uniqueInOrder "ABBCcAD"         == "ABCcAD"
uniqueInOrder [1,2,2,3,3]       == [1,2,3]

unique_in_order("AAAABBBCCDAABBB") == ['A', 'B', 'C', 'D', 'A', 'B']
unique_in_order("ABBCcAD")         == ['A', 'B', 'C', 'c', 'A', 'D']
unique_in_order([1,2,2,3,3])       == [1,2,3]

Solutions

🐍 Python

def unique_in_order(iterable):
    return [] if not iterable else [ i for n, i in enumerate(iterable) if n == 0 or i != iterable[n-1] ]