# --------------------------------------
# Joy and Beauty of Data
# John Paxton
# June 1, 2017
# --------------------------------------
# Simulate dealing 2 BlackJack cards and
# plotting the results.
# --------------------------------------

import numpy as np
import matplotlib.pyplot as plt

# --------------------------------------
# evaluate
# --------------------------------------
# card: a playing card represented by 0 - 51
# --------------------------------------
# Returns: the value of the card, an integer
# --------------------------------------
# Aces count 11, Kings/Queens/Jacks count
# 10, all other cards count face value.
# --------------------------------------


def evaluate(card):
    if (2 <= card % 13 <= 10):      # face value
        return card % 13
    elif (card % 13 == 1):          # ace
        return 11
    else:                           # jack, queen or king
        return 10

# --------------------------------------
# generateAndScoreHand
# --------------------------------------
# Returns: the value of 2 cards, an integer
# --------------------------------------
# Randomly generate a 2-card BlackJack hand
# from a regular 52 card deck and then determine
# its value.
# --------------------------------------

def generateAndScoreHand():
    card1 = np.random.randint(52)
    card2 = np.random.randint(52)
    
    while (card1 == card2):             # the cards must be different
        card2 = np.random.randint(52)

    value = evaluate(card1) + evaluate(card2)
    
    if (value == 22):                   # readjust score for 2 aces
        value = 12

    return value

# --------------------------------------
# generateHands
# --------------------------------------
# howMany: the number of Blackjack hands to generate, an integer
# --------------------------------------
# Returns: the values of each hand, a numpy array
# --------------------------------------

def generateHands(howMany):
    result = np.ndarray([howMany], dtype='int')
    
    for hand in range(howMany):
        result[hand] = generateAndScoreHand()
        
    return result

# --------------------------------------
# handCounts
# --------------------------------------
# hands: the value of each 2-card BlackJack hand, a numpy array
# --------------------------------------
# Hands can score 4 through 21.  Determine and
# print the number of hands for each value.
# --------------------------------------

def handCounts(hands):
    counts = np.zeros([22], dtype=int)  # slots 0 through 3 unused
    
    for hand in hands:
        counts[hand] += 1
        
    for i in range(4, 22):
        print(i, counts[i])

# --------------------------------------

hands = generateHands(10000)
handCounts(hands)

plt.hist(hands, bins=np.arange(4, 23), normed=True, facecolor='red', align='left')  # generate histogram
plt.xticks(np.arange(4, 22))
plt.xlim(3.5, 21.5)
plt.xlabel('Hand Value')
plt.ylabel('Probability')
plt.title('Histogram of 2-Card BlackJack Hands')
plt.grid(True)
plt.show()