Check if all items of a list of string are grouped. ['a', 'a', 'b'] are, ['a', 'b, 'a'] are not.

are_strings_grouped.py

def are_strings_grouped(list_of_strings):
    # First find the number of expected changes
    n_unique_strings = len(set(list_of_strings))
    n_expected_changes = n_unique_strings - 1
    # Then find the real number of changes
    groups_channges = [1 for former, latter
                       in zip(list_of_strings[:-1], list_of_strings[1:])
                       if former != latter]
    n_real_changes = sum(groups_channges)
    # Finally compare them
    return n_real_changes == n_expected_changes

# Grouped:
# _list_of_strings = ['a', 'a', 'a', 'b', 'b', 'b', 'c']
# _list_of_strings = ['a', 'a', b']
# _list_of_strings = ['a', 'b', b']
# _list_of_strings = ['a', 'b', c']
# _list_of_strings = ['a', 'b']
# _list_of_strings = ['a', 'a']
# _list_of_strings = ['a']
#
# Not Grouped:
# _list_of_strings = ['a', 'a', 'a', 'b', 'b', 'b', 'a']
# _list_of_strings = ['a', 'b', 'a', 'b', 'b', 'b', 'c']
# _list_of_strings = ['a', 'b', 'a', 'c', 'b', 'c', 'd']
# _list_of_strings = ['a', 'b', 'a', 'b', 'a', 'b', 'a']
# _list_of_strings = ['a', 'b', a']