python - python 文件上的随机选择不起作用

Question

我正在尝试用 Python 进行闪存卡测验挑战。这涉及从文本文件中获取州及其首府。我已经成功地进行剥离和拆分，以便创建带有键的字典。

但是每次我在 for 循环中使用随机选择时，它都会输出最后一个键(例如怀俄明州)，另一方面，当我将其从 for 循环中取出时，它只输出第一个键(例如阿拉巴马州)

这是它的样子(显然这不显示文本文件)

import random
with open("state_capitals.txt","r") as f:
for line in f:
    cleanedLine = line.strip().split(',')
    state = cleanedLine[0]
    capital = cleanedLine[1]
    d = {}
    d[state] = capital
    while len(d)>0:
        choice = random.choice(list(d.keys()))

        print("What is the capital city of",choice,"?")
        answer=input("Answer:  ")

Answer 1

问题是 while 循环位于 for 循环的范围内，因此您永远没有机会填充字典。但是，将 while 循环移到 for 循环之外并不能解决不同的问题；您在 for 循环中初始化 d ，以便它不断重置回空字典，删除所有以前的条目。

import random

d = {} # Create the dict once, otherwise each loop will delete all previous entries

with open("state_capitals.txt","r") as f:
    for line in f:
        cleanedLine = line.strip().split(',')
        state = cleanedLine[0]
        capital = cleanedLine[1]
        d[state] = capital

# Move this outside the while loop. There's no need to recreate it on every iteration
states = list(d.keys())

# Move the while loop to be outside of the for loop
while len(d)>0:
    choice = random.choice(states)

    print("What is the capital city of",choice,"?")
    answer=input("Answer:  ")

    # Allow the user to type Quit/quit to break the loop
    if answer.lower() == 'quit':
        break