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#| default_exp card

card--A basic playing card¶

A simple API for creating and using playing cards

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#| export
from fastcore.utils import *

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#| hide
from nbdev.showdoc import *
from fastcore.test import *

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#| export
suits = ["♣️","♦️","❤️","♠️"]
ranks = [None, "A"] + [str(x) for x in range(2,11)]  + ["J", "Q", "K"]

We will be using numbers to represent playing card clubs and ranks. These are the suits:

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suits

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['♣️', '♦️', '❤️', '♠️']

For instance the suit at index 0:

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suits[0]

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'♣️'

These are the ranks:

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ranks

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[None, 'A', '2', '3', '4', '5', '6', '7', '8', '9', '10', 'J', 'Q', 'K']

For instance the rank at index 1 (note that there isn't a playing card at position 0, since we want the ranks to match the indicies where possible):

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ranks[1]

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'A'

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#| export
class Card:
    "A playing card"
    def __init__(self,
                 suit:int,  # An index into `suits`
                 rank:int): # An index into `ranks`
        self.suit,self.rank = suit,rank
    def __str__(self): return f"{ranks[self.rank]}{suits[self.suit]}"
    __repr__ = __str__

Here's an example of creating and displaying a card:

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c = Card(suit=1, rank=3)
c

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3♦️

Comparison operators¶

Equality, less than, and greater than work on the rank and suit indices.

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#| export
@patch
def __eq__(self:Card, a:Card): return (self.suit,self.rank)==(a.suit,a.rank)
@patch
def __lt__(self:Card, a:Card): return (self.suit,self.rank)<(a.suit,a.rank)
@patch
def __gt__(self:Card, a:Card): return (self.suit,self.rank)>(a.suit,a.rank)

For instance, here's a test of equality...

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test_eq(Card(suit=1, rank=3), Card(suit=1, rank=3))

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#| hide
test_ne(Card(suit=2, rank=3), Card(suit=1, rank=3))
test_ne(Card(suit=1, rank=2), Card(suit=1, rank=3))

...and a test of <...

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assert Card(suit=1, rank=3)<Card(suit=2, rank=3)

...and finally of >:

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assert Card(suit=3, rank=3)>Card(suit=2, rank=3)
assert not Card(suit=1, rank=3)>Card(suit=2, rank=3)

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