概率不加到 1

Question

我想知道是否可以在查看第二个 for 循环时获得一些帮助。在这种情况下，骰子是不公平的，我为偶数分配了很大的权重。代码有两个问题：概率加起来不为 1，奇数的概率大于偶数。

import random

NUM_ROLLS = 100
DIE_SIDES = [1,3,2,4,4,6]
odd_roll_result = 0
even_roll_result = 0
probability = 0

# Create the dictionary to store the results of each roll of the die.
rolls = {}

#Loop for rolling the die NUM_ROLLS times
for r in range(NUM_ROLLS):

    roll_result = random.randint(0,len(DIE_SIDES)-1) 
    if roll_result in rolls:
        # Add to the count for this number.
        rolls[roll_result] += 1    
    else:
        # Record the first roll result for this number.
        rolls[roll_result] = 1
    #print(DIE_SIDES[roll_result])

# Print how many times each number was rolled
for roll_result in range(len(DIE_SIDES)):

#    print("The number", str(roll_result).format(roll_result, DIE_SIDES[roll_result]),
#          "was rolled", str(rolls[roll_result]), "times.")
    print("The number", roll_result, DIE_SIDES[roll_result],
          "was rolled", str(rolls[roll_result]), "times.")
    if roll_result == 1 or  roll_result == 3 or roll_result == 5:
        odd_roll_result = odd_roll_result + rolls[roll_result]
        #print(odd_roll_result)
    if roll_result == 2 or  roll_result == 4 or roll_result == 6:
        even_roll_result = even_roll_result + rolls[roll_result]
        #print(even_roll_result)

probability_odd = odd_roll_result/NUM_ROLLS
th_exp = 1/6 
prob_th = abs(th_exp-probability_odd)
probability_even = even_roll_result/NUM_ROLLS

print("The probability of getting an odd number is " , probability_odd )
print("Theoretical probability of getting an odd number is " , prob_th )
print("The probability of getting an even number is " , probability_even )

Answer 1

首先，正如其他评论者所指出的，您应该修改 DIE_SIDES 的定义：

DIE_SIDES = [1,2,3,4,5,6]

然后像这样改变掷骰子的线：

roll_result = random.randint(1,len(DIE_SIDES))

甚至更好：

roll_result = random.choice(DIE_SIDES)

Answer 2

您的代码将 0 视为 roll_result，但不将其计入 odd_roll_result 或 even_roll_result。这就是概率加起来不为 1 的原因。

概率不加到 1

Probability not adding to 1

python

probability