def find_unique_common_from_lists(input_list1, input_list2, only_com=False):
	'''
	find common items from 2 lists, the returned elements are unique. repetitive items will be ignored
	if the common items in two elements are not in the same order, the outputs follows the order in the first list

	parameters:
		input_list1, input_list2:		two input lists
		only_com:		True if only need the common list, i.e., the first output, saving computational time

	outputs:
		list_common:	a list of elements existing both in list_src1 and list_src2	
		index_list1:	a list of index that list 1 has common items
		index_list2:	a list of index that list 2 has common items
	'''

	common_list = list(set(input_list1).intersection(input_list2))

	if only_com: return common_list

	# find index
	index_list1 = []
	for index in range(len(input_list1)):
		item = input_list1[index]
		if item in common_list:
			index_list1.append(index)

	index_list2 = []
	for index in range(len(input_list2)):
		item = input_list2[index]
		if item in common_list:
			index_list2.append(index)

	return common_list, index_list1, index_list2