我要订购错误的清单吗

Question

I have trying to generate a deck of cards that print out a list of 7 values and then I want to put the list into order. I am a basic python coder and working my way through a python for beginners book I bought.

import random
for x in range(7):
    rank = random.choice( ('A','2','3','4','5','6','7','8','9','T','J','Q','K') )
    suit = random.choice( ('c','d','h','s') )
    card = rank + suit
    print(card)

how could I put the list into order or am I completely wrong

Answer 1

import random

#create an empty list
y = list()

# continue picking cards until you have 7 cards -> avoid duplicates
while len(y) < 7:
    rank = random.choice(('A','2','3','4','5','6','7','8','9','T','J','Q','K'))
    suit = random.choice( ('c','d','h','s') )
    card = rank + suit

    #if the card is not present in the list, add it 
    if not card in y:
        y.append(card)

        #sort your list (by 1st letter -> no sort criteria were given)
        y = sorted(y)

print(y)

Answer 2

Use itertools.product to generate the full deck of cards. It basically gives you a sequence of every element of the first iterable with every element of the second iterable. You can then shuffle the deck using random.shuffle , just like you would a real deck.

Then take a slice of the first 7 elements and perform a sort on them.

To sort you will need to provide a key function, as the natural sort order is not what you want. We can provide a tuple as a return value of the key function and it acts as a tie breaker for when the first character is the same. What we want to sort on is the index of a particular character in the input tuple s ( rank , suit ).

The first sorting key just uses the tuple.index method to get the indexes of the particular characters in the tuples . This is simple but it is slow, as it has to count up the tuple every time (O(n) or linear time complexity). Those indices never change, so we can precompute them into a dict and get constant time look up in the key function, which is faster. For applications like this where the tuples are small and number of calculations are small the gains may not be so significant, so either solution is probably acceptable.

I did the sort as rank first then suit. Your question doesnt specify either way, but perhaps sorting them suit is what you want? In which case you should find it a useful exercise to convert the key functions.

Here's the code

from itertools import product
from random import choice, shuffle

rank = ('A','2','3','4','5','6','7','8','9','T','J','Q','K')
suit = ('c','d','h','s')

# make the full deck in the format of a 2 char string
deck = [r+s for r,s in product(rank, suit)]

# inplace shuffle of card
shuffle(deck)

# take the first 7 (we know there will be that many)
hand = deck[:7]

print(hand)

# sorting

# first way, slow but simpler
keyfn = lambda c: (rank.index(c[0]), suit.index(c[1]))
sortedhand = sorted(hand, key=keyfn)

print(sortedhand)

# second way, faster but more complex
def mkkeyfn():
    rankmap = {v: i for i, v in enumerate(rank)}
    suitmap = {v: i for i, v in enumerate(suit)}
    def keyfn(val):
        rank, suit = val
        return rankmap[rank], suitmap[suit]
    return keyfn

sortedhand2 = sorted(hand, key=mkkeyfn())
print(sortedhand2)