Xjyuk

Inspired by the video from Scam Nation and James Grime from Numberphile, I tried to make a Razzle Dazzle simulator.

Razzle Dazzle is a scam in the form of a game. Per turn, the player pays a fee and throws 8 marbles onto a board, so they land in holes in the board. Each hole has a score from 1 to 6. Throwing 8 dice instead can also be done. The scores are added to form a score from 8 to 48. This score is translated into points via table/chart. The points are accumulated across turns. When the player reaches 100 points, it wins a prize. Some scores increase the number of prizes when 100 points are reached. A score of 29 doubles the fee per turn, multiplicatively, so scoring 29 10 times increases the fee to 1024x the initial fee.

The trick is that the most common scores (22-34) do not give any points. This means that only 2.7% of the turns by fair dice rolls give out points, needing 369.5 turns to reach 100 points. For the board in the video, only 0.28% give points, resulting in 5000+ turns to get 100 points. The probability to score 29 is about 8%, this leads to massive fees when playing lots of turns.

import random, numpy
import matplotlib.pyplot as plt

# return one int with random value [1,6], with the probability density described in rawMassDist
# every 1000 turns, sample 1000 loaded die throws and put them in a list
randoms = []
idxRandom = 0
def throwLoadedDie():
 global idxRandom
 global randoms
 rawMassDist = [11, 17, 39, 44, 21, 11]
 #rawMassDist = [50, 5, 5, 5, 5, 50]
 massDist = [float(i)/sum(rawMassDist) for i in rawMassDist]
 if (idxRandom % 1000) == 0:
 #randoms = numpy.random.choice(range(1, 7), size=1000, p=massDist)
 randoms = random.choices(range(1,7), massDist, k=1000)
 idxRandom = 0
 idxRandom += 1
 return randoms[idxRandom-1]

# throw 8 dice, fairDice indicates whether fair dice or loaded dice are used
# returns the sum of the dice values, which equals the score for this turn
def throwDice():
 total = 0
 for _ in range(0,8):
 if fairDice:
 total += random.randint(1,6);
 else:
 total += throwLoadedDie()
 return total

# translates the score into points using dictionary toPoints
def getPoints(score):
 toPoints = 8:100, 9:100, 10:50, 11:30, 12:50,
 13:50, 14:20, 15:15, 16:10, 17:5, 
 39:5, 40:5, 41:15, 42:20, 43:50, 
 44:50, 45:50, 46:50, 47:50, 48:100
 if score in toPoints:
 return toPoints[score]
 return 0

# returns if this score results in an extra price
def isExtraPrize(score):
 if (18 <= score <= 21) or (score == 29) or (35 <= score <= 38):
 return True
 return False

# returns if this score doubles the fee for one turn
def needDoubleFee(score):
 return score == 29

# simulate one turn, return the new number of points, prizes and fee for the next turn
def simulateTurn(points, prizes, fee):
 score = throwDice()
 if isExtraPrize(score):
 prizes += 1
 if needDoubleFee(score):
 fee *= 2
 points += getPoints(score)
 return [points, prizes, fee, score]

# simulate single game, can result in win or loss in maxTurns turns
# can print result and histogram of scores
def playGame(printResult = True, maxTurns = 1000):
 points = 0
 prizes = 1
 hist = list() # start with empty list, add score after every turn
 hist2 = [0]*49 # entries 0-7 is always 0, other entries 8-48 represent the number of times a score has occurred
 fee = 1
 totalFee = 0
 goal = 100
 won = False
 for turn in range(1, maxTurns+1):
 #print('Turn 0, points: 1'.format(turn, points))
 totalFee += fee
 [points, prizes, fee, score] = simulateTurn(points, prizes, fee)
 hist.append(score)
 if points >= goal:
 won = True
 break

 # finalize
 [hist2, _] = numpy.histogram(hist, bins=49, range=[0,48])
 if printResult:
 if won:
 print('You win 0 prizes in 1 turns, cost: 2'.format(prizes, turn, totalFee))
 else:
 print('You only got 0 points in 1 turns, cost: 2'.format(points, turn, totalFee))

 print(hist2)
 if not won:
 prizes = 0
 return [prizes, turn, totalFee, hist2]

# simulate multiple games, allow many turns per game to practically ensure win
# also disable result printing in each game
def playGames(numGames, plot=False):
 hist = [0]*49
 totalPrizes = 0
 totalTurns = 0
 totalFee = 0
 withPoints = 0
 gamesLost = 0
 for i in range(0, numGames):
 [prizes, turns, fee, hist2] = playGame(False, 100000)
 if prizes == 0:
 gamesLost += 1
 hist = [x + y for x, y in zip(hist, hist2)]
 totalPrizes += prizes
 totalFee += fee
 totalTurns += turns
 for i in range(8, 18):
 withPoints += hist[i]
 for i in range(39, 49):
 withPoints += hist[i]
 print('0 games, lost 1'.format(numGames, gamesLost))
 print('Avg prizes: '.format(totalPrizes/numGames))
 print('Avg turns: '.format(totalTurns/numGames))
 print('Avg fee: '.format(totalFee/numGames))
 print(hist)
 print('Percentage turns with points: :.2f'.format(100.0*withPoints/sum(hist)))

 if plot:
 # create list of colors to color each bar differently
 colors = [item for sublist in [['red']*18, ['blue']*21, ['red']*10] for item in sublist]
 plt.bar(range(0, 49), hist, color=colors)
 plt.title('Score distribution across multiple games')
 plt.xlabel('Score = sum of 8 dice')
 plt.ylabel('Number of turns')
 plt.text(40, 0.6*max(hist), 'Red barsngive points')
 plt.show()

fairDice = False
#playGame()
playGames(100, plot=True)

Concrete questions:

1. Since calling random.choices() has some overhead, I generate 1000 loaded die rolls and put it in a global array. Is there a better of doing this without classes? In C I'd probably use static variables

2. To generate a histogram of all the scores during a game, I append to a list every turn, and then generate the histogram. Is this efficient performance-wise?

3. How are my names? Especially hist, hist2, isExtraPrize() and needDoubleFee()

4. My Ryzen 5 2400G with 3200 MHz RAM takes about 15s to simulate 100 loaded games, averaging
3550 turns per game. I somehow feel like this should be faster, any performance related suggestions are welcome

5. And of course, general code review answers are welcome

First, your use of camelCase isn't ideal in Python. For variable and function names, snake_case is preferred. I'll be using that with any re-written code that I show.

I think throw_dice can be improved a bit. You're checking for the value of fair_dice once per iteration in the function instead of once at the beginning. This will be negligible performance-wise, but it's unnecessary and checking once per loop suggests that it's a value that can change in the loop, which isn't the case here.

There's different ways of approaching this depending on how close to PEP you want to adhere to; but both ways I'll show depend on dispatching to a function using a conditional expression. Following PEP, you could do something like:

def throw_loaded_die():
 return 1 # For brevity

# Break this off into its own function
def throw_fair_die():
 return random.randint(1, 6)

def throw_dice():
 # Figure out what we need first
 roll_f = throw_fair_die if fair_dice else throw_loaded_die

 total = 0
 for _ in range(8):
 total += roll_f() # Then use it here

 return total

That cuts down on duplication which is nice. I also got rid of the 0 argument in the call to range as that's implicit if it isn't specified.

I think the separate def throw_fair_die is unfortunate though. For such a simple function, I find it to be noisy, and looking around, I'm not the only one to feel this way. Personally, I'd prefer to just write:

def throw_dice():
 # Notice the lambda
 roll_f = (lambda: random.randint(1, 6)) if fair_dice else throwLoadedDie

 total = 0
 for _ in range(8): # Specifying the start is unnecessary when it's 0
 total += roll_f()

 return total

This is arguably a "named lambda" though, which is in violation of the recommendations of PEP:

Always use a def statement instead of an assignment statement that binds a lambda expression directly to an identifier.

¯_(ツ)_/¯

I still think it can be improved though. Look carefully at the loop. It's just a summing loop! Python has a built-in for that that can be used cleanly with a generator expression:

def throw_dice():
 roll_f = throw_fair_die if fair_dice else throw_loaded_die

 return sum(roll_f() for _ in range(8))

is_extra_prize has a redundant return. It can be simplified to:

def is_extra_prize(score):
 return (18 <= score <= 21) or (score == 29) or (35 <= score <= 38)

I'll point out though that right below it you have need_double_fee. Either it's justified to have score == 29 broken off into its own function (in which case it should be used in the appropriate cases), or it's not. If you feel the need to have it as a separate function, I'd use it:

def need_double_fee(score):
 return score == 29

def is_extra_prize(score):
 return (18 <= score <= 21) or need_double_fee(score) or (35 <= score <= 38)

Although it could be argued that the other two parts of the condition in is_extra_prize are more complicated than score == 29, and may benefit from having a name attached to them as well. There's also the alternative of naming the 29 magic number directly, which I feel would probably be an even better option:

EXTRA_PRIZE_SCORE = 29

def is_extra_prize(score):
 return (18 <= score <= 21) or score == EXTRA_PRIZE_SCORE or (35 <= score <= 38)

You may find naming 18, 21, 35 and 38 are beneficial as well; although that will certainly make that function more verbose.

I think get_points can be improved as well. The score dictionary seems like it's a "member of the entire program", not something that should be local to the function. You can also use get on the dictionary to avoid the explicit membership lookup:

SCORE_TO_POINTS = 8:100, 9:100, 10:50, 11:30, 12:50,
 13:50, 14:20, 15:15, 16:10, 17:5, 
 39:5, 40:5, 41:15, 42:20, 43:50, 
 44:50, 45:50, 46:50, 47:50, 48:100

def get_points(score):
 # 0 is the default if the key doesn't exist
 return SCORE_TO_POINTS.get(score, 0)

simulate_turn returns a tuple (actually a list, although it probably should be a tuple) representing the new state of the game. This is fine for simple states, but your current state has four pieces, and accessing them requires memorizing what order they're in, and allows mistakes to be made if data is placed incorrectly. You may want to look into using a class here for organization and clarity, or even a named tuple as a shortcut.

In that same function, I'd also add some lines to space things out a bit:

def simulate_turn(points, prizes, fee):
 score = throwDice()

 if isExtraPrize(score):
 prizes += 1

 if needDoubleFee(score):
 fee *= 2

 points += getPoints(score)

 return (points, prizes, fee, score)

Personal style, but I like open space in code.

You could also do away with the mutation of the parameters:

def simulate_turn(points, prizes, fee):
 score = throwDice()

 return (points + getPoints(score),
 prizes + 1 if isExtraPrize(score) else prizes,
 fee * 2 if needDoubleFee(score) else fee,
 score)

Although now that it's written out, I'm not sure how I feel about it.

I really only dealt with 5. here. Hopefully someone else can touch on the first four points.