all possible subset combinations of a set

all_combo.py

# =====================================
# calculate all possible subset for a set
# base prespective for n nested loop and other dynamic problems!
# for i in [0..2]:
#     for j in [0..2]:
#         for p in [0..2]:
#             for q in [0..2]:

# 0 0 0 0 -> 0 0 0 2 -> 0 0 1 0 -> 0 0 1 2
# 0000, 0001, 0002, 0010, 0011, 0012, 0020, ..., 2222, (1)0000
# i j p q ...n ta...
# i1 i2 i3 ... in

# setlst = [[0,1,2], [0,1,2], [0,1,2]]
setlst = [["cs","wo","force", "shi"], ["cs","wo","force", "shi"], ["cs","wo","force", "shi"]]
n = len(setlst)
k = len(setlst[0])
idx = 0
lst = []

# METHOD 1
def select():
    global setlst, lst, idx
    lst = []
    t = idx
    for i in range(n):
        lst.append(setlst[i][t%k])
        t = t//k
    idx += 1
    return idx != n**k+1
while select():
    print(lst, "=>" , idx, ''.join(str(i) for i in lst))

# METHOD 2
i = [0 for _ in range(0,n)]
def finished():
    global i
    for j in i:
        if j is not 0:
            return False
    return True
def check():
    global i, k, n
    for j in range(len(i)):
        if i[j] >= k:
            i[j] = 0
            if j+1 < n:
                i[j+1] += 1
def inc():
    global i
    i[0] += 1
    check()

def select():
    global setlst, i, n, k
    tmp = []
    for j in range(len(i)):
        yield setlst[j][i[j]]

print([m for m in select()])
inc()
while not finished():
    print([m for m in select()])
    inc()

# METHOD 3
def com(lst):
    N = len(lst)
    for i in range(2**N):
        combo = []
        for j in range(N):
            if (i >> j) % 2 == 1:
                combo.append(lst[j])
                print(lst[j])
        yield combo

for i in com([1,2,3,5]):
    print(i, ", ", end="")

# METHOD 4 : TODO: fix the bugs and make it faster!!!!!! use multi processing using some AI algo
import copy
lst = [ [1,2,3], [4,5,6], [7,8,9] ]
y, combo, lt = [], [], copy.deepcopy(lst)
def firstElem(lst):
    if len(lst)>0:
        lst.remove(lst[0])
        return lst
    else:
        return
def allCombo(lst):
    global y, combo
    if len(lst)>0:
        a = lst[0][0]
        while a is not None:
            y.append(a)
            allCombo(firstElem(lst))
            lt[0].remove(a)
            a = lt[0][0]
        lt.remove(lt[0])
        allCombo(lt)
    else:
        combo.append(y)
    return combo
print(allCombo(lst))

# =====================================