get_subsets.py

#python 2.7+, 3

def get_subsets_recursive(l, c=0):
	"""
	Recursivemethod
	l is the set of items to get all combination subsets
	c is to track recursion depth for visibility
	"""
	c+=1
	#end recursion loop once at the end of the list
	if not l:
		return [[]]
	#recursively call get_subsets deducting the first item on each successive call
	sublists = get_subsets_recursive(l[1:], c)
	print(("Recursion depth: {}".format(c)))
	print(("Current sublists", sublists))
	#sublist_output will be the new combinations added to the master set (l)
	sublist_output = []
	#for each item in the set, 
	for item in sublists:
		new_combo = [l[0]] + item
		print ("New Combination created: ")
		print(new_combo)
		sublist_output.append(new_combo)
		print ("Output Updated: ")
		print(sublist_output)
	print(('Finished calculating recursion: {}'.format(c)))
	print(('Finished recursion output: {}'.format(sublists+sublist_output)))
	return sublists + sublist_output

def get_subsets_for_loop(l):
	"""
	go through each item and create a tmp list for that item
	for each item on 
	"""
	output_sets = [[]]
	for i,x in enumerate(l):
		#this will store the set of new combinations created with the new item combined with all previously created combinations
		t= []
		#for each item in the exisiting output set combine it with the new item 
		for v,c in enumerate(output_sets):
			t.append(c + [x])
		#append all new combinations to master list
		output_sets+=(t)

	return output_sets







r =  get_subsets_recursive([1,2,3,4,5])

f =  get_subsets_for_loop([1,2,3,4,5])

print('Recursive output: ')
print (r)
"""
[[], [5], [4], [4, 5], [3], [3, 5], [3, 4], [3, 4, 5], [2], [2, 5], [2, 4], [2, 4, 5], [2, 3], [2, 3, 5], [2, 3, 4], [2, 3, 4, 5], [1], [1, 5], [1, 4], [1, 4, 5], [1, 3], [1, 3, 5], [1, 3, 4], [1, 3, 4, 5], [1, 2], [1, 2, 5], [1, 2, 4], [1, 2, 4, 5], [1, 2, 3], [1, 2, 3, 5], [1, 2, 3, 4], [1, 2, 3, 4, 5]]
"""
print('forloop output: ')
"""
[[], [1], [2], [1, 2], [3], [1, 3], [2, 3], [1, 2, 3], [4], [1, 4], [2, 4], [1, 2, 4], [3, 4], [1, 3, 4], [2, 3, 4], [1, 2, 3, 4], [5], [1, 5], [2, 5], [1, 2, 5], [3, 5], [1, 3, 5], [2, 3, 5], [1, 2, 3, 5], [4, 5], [1, 4, 5], [2, 4, 5], [1, 2, 4, 5], [3, 4, 5], [1, 3, 4, 5], [2, 3, 4, 5], [1, 2, 3, 4, 5]]
"""
print (f)