Remove multiple elements from a List

Question

Im having a problem with this python code:

card_list = ["1P", "1C", "1O","1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O", 
     "3E", "4P", "4C", "4O", "4E", "5P", "5C", "5O", "5E", "6P", "6C", "6O", 
     "6E", "7P", "7C", "7O", "7E", "8P", "8C", "8O", "8E", "9P", "9C", "9O", "9E", "DP", 
     "DC", "DO", "DE", "JP", "JC", "JO", "JE", "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE", 
     "1P", "1C", "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O", "3E", 
     "4P", "4C", "4O", "4E", "5P", "5C", "5O", "5E", "6P", "6C", "6O", "6E", "7P", "7C", 
     "7O", "7E", "8P", "8C", "8O", "8E", "9P", "9C", "9O", "9E", "DP", "DC", "DO", "DE", 
     "JP", "JC", "JO", "JE", "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE", "1P", "1C", 
     "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O", "3E", "4P", "4C", "4O", "4E", 
     "5P", "5C", "5O", "5E", "6P", "6C", "6O", "6E", "7P", "7C", "7O", "7E", "8P", "8C", 
     "8O", "8E", "9P", "9C", "9O", "9E", "DP", "DC", "DO", "DE", "JP", "JC", "JO", "JE", 
     "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE"]

#print all cards
print card_list

#cards from a deck
cards_deck = ["1P", "1C", "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O", 
     "3E", "4P", "4C", "4O", "4E", "5P", "5C", "5O", "5E", "6P", "6C", "6O", 
     "6E", "7P", "7C", "7O", "7E", "8P", "8C", "8O", "8E", "9P", "9C", "9O", "9E", "DP", 
     "DC", "DO", "DE", "JP", "JC", "JO", "JE", "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE"]

#remove deck cards from card pool
final_card= list(set(card_list).difference(set(cards_deck)))

#print remaining cards
print final_card

In the end it should just remove one "1P", one "1C", etc but it ends up removing all them and shows an empty array. Anyway I can just show the remaining cards?

The objective is having a big pool of cards, and from that big pool keep removing "cards_deck" like its forming decks until its not possible anymore.

How can I do this?

Answer 1

As @tobias_k mentioned you could use Counter :

from collections import Counter

card_list = ["1P", "1C", "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O",
             "3E", "4P", "4C", "4O", "4E", "5P", "5C", "5O", "5E", "6P", "6C", "6O",
             "6E", "7P", "7C", "7O", "7E", "8P", "8C", "8O", "8E", "9P", "9C", "9O", "9E", "DP",
             "DC", "DO", "DE", "JP", "JC", "JO", "JE", "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE",
             "1P", "1C", "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O", "3E",
             "4P", "4C", "4O", "4E", "5P", "5C", "5O", "5E", "6P", "6C", "6O", "6E", "7P", "7C",
             "7O", "7E", "8P", "8C", "8O", "8E", "9P", "9C", "9O", "9E", "DP", "DC", "DO", "DE",
             "JP", "JC", "JO", "JE", "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE", "1P", "1C",
             "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O", "3E", "4P", "4C", "4O", "4E",
             "5P", "5C", "5O", "5E", "6P", "6C", "6O", "6E", "7P", "7C", "7O", "7E", "8P", "8C",
             "8O", "8E", "9P", "9C", "9O", "9E", "DP", "DC", "DO", "DE", "JP", "JC", "JO", "JE",
             "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE"]

# print all cards
print card_list

# cards from a deck
cards_deck = ["1P", "1C", "1O", "1E", "2P", "2C", "2O", "2E", "3P", "3C", "3O",
                  "3E", "4P", "4C", "4O", "4E", "5P", "5C", "5O", "5E", "6P", "6C", "6O",
                  "6E", "7P", "7C", "7O", "7E", "8P", "8C", "8O", "8E", "9P", "9C", "9O", "9E", "DP",
                  "DC", "DO", "DE", "JP", "JC", "JO", "JE", "VP", "VC", "VO", "VE", "RP", "RC", "RO", "RE"]

counts = Counter(card_list)

while counts:

    # remove deck cards from card pool
    for card in cards_deck:
        counts[card] -= 1
        if counts[card] == 0:
            counts.pop(card)

    final_card = [card for card in counts.elements()]

    # print remaining cards
    print final_card

Output

['1P', '1C', '1O', '1E', '2P', '2C', '2O', '2E', '3P', '3C', '3O', '3E', '4P', '4C', '4O', '4E', '5P', '5C', '5O', '5E', '6P', '6C', '6O', '6E', '7P', '7C', '7O', '7E', '8P', '8C', '8O', '8E', '9P', '9C', '9O', '9E', 'DP', 'DC', 'DO', 'DE', 'JP', 'JC', 'JO', 'JE', 'VP', 'VC', 'VO', 'VE', 'RP', 'RC', 'RO', 'RE', '1P', '1C', '1O', '1E', '2P', '2C', '2O', '2E', '3P', '3C', '3O', '3E', '4P', '4C', '4O', '4E', '5P', '5C', '5O', '5E', '6P', '6C', '6O', '6E', '7P', '7C', '7O', '7E', '8P', '8C', '8O', '8E', '9P', '9C', '9O', '9E', 'DP', 'DC', 'DO', 'DE', 'JP', 'JC', 'JO', 'JE', 'VP', 'VC', 'VO', 'VE', 'RP', 'RC', 'RO', 'RE', '1P', '1C', '1O', '1E', '2P', '2C', '2O', '2E', '3P', '3C', '3O', '3E', '4P', '4C', '4O', '4E', '5P', '5C', '5O', '5E', '6P', '6C', '6O', '6E', '7P', '7C', '7O', '7E', '8P', '8C', '8O', '8E', '9P', '9C', '9O', '9E', 'DP', 'DC', 'DO', 'DE', 'JP', 'JC', 'JO', 'JE', 'VP', 'VC', 'VO', 'VE', 'RP', 'RC', 'RO', 'RE']
['1P', '1P', 'DO', 'DO', '3P', '3P', 'JP', 'JP', '5P', '5P', 'VC', 'VC', '3C', '3C', '1C', '1C', 'JO', 'JO', '1E', '1E', '5E', '5E', 'JE', 'JE', '8E', '8E', '3E', '3E', 'JC', 'JC', '7E', '7E', '2O', '2O', '7C', '7C', '9O', '9O', '7O', '7O', '9C', '9C', '9E', '9E', 'RE', 'RE', '5C', '5C', '7P', '7P', '9P', '9P', 'RO', 'RO', 'DE', 'DE', '2P', '2P', 'VE', 'VE', 'RC', 'RC', '4P', '4P', 'DC', 'DC', 'VP', 'VP', '4O', '4O', '2C', '2C', 'RP', 'RP', '4E', '4E', '4C', '4C', '8O', '8O', '1O', '1O', '6C', '6C', '6E', '6E', 'DP', 'DP', '2E', '2E', '8C', '8C', '5O', '5O', '6O', '6O', '6P', '6P', 'VO', 'VO', '3O', '3O', '8P', '8P']
['1P', 'DO', '3P', 'JP', '5P', 'VC', '3C', '1C', 'JO', '1E', '5E', 'JE', '8E', '3E', 'JC', '7E', '2O', '7C', '9O', '7O', '9C', '9E', 'RE', '5C', '7P', '9P', 'RO', 'DE', '2P', 'VE', 'RC', '4P', 'DC', 'VP', '4O', '2C', 'RP', '4E', '4C', '8O', '1O', '6C', '6E', 'DP', '2E', '8C', '5O', '6O', '6P', 'VO', '3O', '8P']
[]

Explanation

The idea is to decrease the count of each card in card_deck for each iteration of the while loop until you have no cards present in counts . When the count of a card gets to 0 remove it from counts .

Answer 2

The reason for your problem is that set takes distinct elements from the list and hence you end up subtracting two sets of distinct elements which have all the elements common among them. Hence your set difference is an empty set.

You can solve your problem as such.

final_card = filter(None, [each if each not in cards_deck else cards_deck.remove(each) for each in card_list ])

EDIT :

To find the total number of decks you can make from the cards.

from collections import Counter
card_counter = Counter(card_list)
check_if_all_cards_exist = set(card_list).difference(cards_deck)
if check_if_all_cards_exist:
   number_of_decks = min(card_counter.values())
else:
   number_of_decks = 0

Answer 3

Hope this answers your problem. I've created a new list which only consists the elements which are not present in cards_deck .

print("CARDLIST:",len(card_list))
print("CARD_DECK:",len(cards_deck))

final_card = [card_list[card_list.index(card)] for card in cards_deck if card in card_list]

print("AFTER DIFFERENCE:" ,len(card_list) - len(final_card))

print(final_card)

Output:

CARDLIST: 156
CARD_DECK: 51
AFTER DIFFERENCE: 105
['7E', '1P', '1C', '1O', '1E', '2P', '2C', '2O', '2E', '3P', '3C', '3O', '3E', '4P', '4C', '4O', '4E', '5P', '5C', '5O', '5E', '6P', '6C', '6O', '6E', '7P', '7C', '7O', '7E', '8P', '8C', '8O', '8E', '9P', '9C', '9O', '9E', 'DP', 'DC', 'DO', 'DE', 'JP', 'JC', 'JO', 'JE', 'VP', 'VC', 'VO', 'VE', 'RP', 'RC', 'RO', 'RE', '1P', '1C', '1O', '1E', '2P', '2C', '2O', '2E', '3P', '3C', '3O', '3E', '4P', '4C', '4O', '4E', '5P', '5C', '5O', '5E', '6P', '6C', '6O', '6E', '7P', '7C', '7O', '7E', '8P', '8C', '8O', '8E', '9P', '9C', '9O', '9E', 'DP', 'DC', 'DO', 'DE', 'JP', 'JC', 'JO', 'JE', 'VP', 'VC', 'VO', 'VE', 'RP', 'RC', 'RO', 'RE']