PYTHON:错误消息random.py？以前有用，后来没用了，现在又不行了。怎么回事？

Question

我已经学了几个月的python了，通常我都能克服我面临的所有问题，但现在我不知所措。我正在编写一个名为“Quizzer”的程序，它将用于根据Python给出的术语和答案的列表生成随机问题。 我的主要问题是我一直在研究的gen_question函数。我希望Python接收一个术语，并输出四个多选答案：一个是实际答案，三个是从所有可能答案中随机选择的。我必须包括几个检查，以确保所选的随机答案不是真正的答案，并且彼此不相同。在

我今天终于让它工作了，过了一会儿我测试了一下。我收到一条错误消息（我将在一秒钟内显示）。我把所有的东西都拆开回到了我之前的位置，我仍然得到同样的错误信息。几个小时后我回来了，我又得到了它。出于沮丧，我再试了一次，结果成功了。现在它不工作了。拜托，有人吗：发生什么事了？在

这是我的代码（我不知道有什么必要，所以我包括了整个代码）：

#import random for generating
import random

#term and definition libraries
terms_ans ={'term1':'answer1','term2':'answer2','term3':'answer3','term4':'answer4','term5':'answer5','term6':'answer6','term7':'answer7','term8':'answer8','term9':'answer9','term10':'answer10','term11':'answer11','term12':'answer12','term13':'answer13','term14':'answer14','term15':'answer15','term16':'answer16','term17':'answer17','term18':'answer18','term19':'answer19','term20':'answer20'}
term_list = ['term1','term2','term3','term4','term5','term6','term7','term8','term9','term10','term11','term12','term13','term14','term15','term16','term17','term18','term19','term20']
answer_list = ['answer1','answer2','answer3','answer4','answer5','answer6','answer7','answer8','answer9','answer10','answer11','answer12','answer13','answer14','answer15','answer16','answer17','answer18','answer19','answer20']

#picks the test questions to ask
def gen_test(amount=len(term_list)):
    found_starter = False
    test_terms = []
    while found_starter == False:
        #pick a random starting point in the terms to see if it is suitable
        start_point = random.randint(1, len(term_list))
        if amount == len(term_list):
            #if user inputs max amount of questions possible, just take the term list
            test_terms = term_list
            found_starter = True
        elif len(term_list) - (start_point + amount) >= 0:
            #if it is suitable, then append the terms to the test questions
            for x in xrange(start_point,start_point+amount):
                test_terms.append(term_list[x])
            found_starter = True
    else:
        return test_terms

#scramble list
def list_scrambler(unscrambled_list):
    test_terms=[]
    countdown = len(unscrambled_list) + 1
    for x in range(1, countdown):
        transfer_var = random.randint(0,len(unscrambled_list)-1)
        test_terms.append(unscrambled_list[transfer_var])
        del unscrambled_list[transfer_var]
    return test_terms

#ask user for amount of questions needed and get the list
test_terms = list_scrambler(gen_test(int(raw_input("How many questions on your test? (There are " + str(len(term_list)) + " questions in total.) "))))



def gen_question(picked_term, question_num=1, total_amount=len(test_terms)):
    #print start of question
    print
    print "Question " + str(question_num) + " of " + str(total_amount) + ":"
    print
    print picked_term
    print
    #gather random multiple choice answers they must a) all be different and b) not be the answer
    ans_1_acceptable = False
    while ans_1_acceptable == False:
        int_rand_ans_1 = random.randint(1, len(term_list)) - 1
        if str(term_list[int_rand_ans_1]) != str(picked_term):
            #Term accepted; send to output
            ans_1_acceptable = True
    ans_2_acceptable = False
    while ans_2_acceptable == False:
        int_rand_ans_2 = random.randint(1, len(term_list)) - 1
        if int_rand_ans_2 != int_rand_ans_1 and str(term_list[int_rand_ans_2]) != str(picked_term):
            ans_2_acceptable = True
    ans_3_acceptable = False
    while ans_3_acceptable == False:
        int_rand_ans_3 = random.randint(1, len(term_list)) - 1
        if int_rand_ans_3 != int_rand_ans_1 and int_rand_ans_3 != int_rand_ans_2 and str(term_list[int_rand_ans_3]) != str(picked_term):
            ans_3_acceptable = True
    #Decide if the correct answer is A, B, C, or D
    correct_ans = random.randint(1,4)
    #Print the options using the variables gathered above
    if correct_ans != 1:
        print "A) " + answer_list[int_rand_ans_1]
    else:
        print "A) " + terms_ans[picked_term]
    if correct_ans != 2:
        print "B) " + answer_list[int_rand_ans_2]
    else:
        print "B) " + terms_ans[picked_term]
    if correct_ans != 3:
        print "C) " + answer_list[int_rand_ans_3]
    else:
        print "C) " + terms_ans[picked_term]
    if correct_ans == 1:
        print "D) " + answer_list[int_rand_ans_1]
    elif correct_ans == 2:
        print "D) " + answer_list[int_rand_ans_2]
    elif correct_ans == 3:
        print "D) " + answer_list[int_rand_ans_3]
    else:
        print "D) " + terms_ans[picked_term]

    print

现在，通常情况下，它会像你期望的那样输出所有东西。我还没有自动生成问题的功能，所以我必须输入以下行：

^{2}$

或者不管我用什么术语。在

以下是我得到的输出：

How many questions on your test? (There are 20 questions in total.) 20
>>> gen_question('term1')

Question 1 of 20:

term1


Traceback (most recent call last):
  File "<pyshell#0>", line 1, in <module>
    gen_question('term1')
  File "C:\Users\Owner\Desktop\LEARNING PYTHON\scripts\in progress\Quizzer.py", line 69, in gen_question
    int_rand_ans_1 = random.randint(1, len(term_list)) - 1
  File "C:\Users\Owner\Desktop\LEARNING PYTHON\python 2.7.5\lib\random.py", line 241, in randint
    return self.randrange(a, b+1)
  File "C:\Users\Owner\Desktop\LEARNING PYTHON\python 2.7.5\lib\random.py", line 217, in randrange
    raise ValueError, "empty range for randrange() (%d,%d, %d)" % (istart, istop, width)
ValueError: empty range for randrange() (1,1, 0)
>>> gen_question('term8')

Answer 1

很明显，randint()在抱怨，因为{}是空的，对吧？那么

random.randint(1, len(term_list))

是

^{pr2}$

并且randint被卡住了。那么为什么是空的？因为这句话：

test_terms = list_scrambler(gen_test(int(raw_input("How many questions on your test? (There are " + str(len(term_list)) + " questions in total.) "))))

破坏term_list，这可能是；-）无意的。在

很难按照代码来追踪为什么会发生这种情况。基本问题是gen_test可以设置

test_terms = term_list

然后以名称test_terms返回{}。那么term_list在list_scrambler的开头仍然是完整的，但是在list_scrambler结束时是空的。在

        del unscrambled_list[transfer_var]

一次删除term_list中的所有元素。在

Answer 2

这就是你想要的：

term_list = [...]

在文件开始时定义，但稍后当输入的金额为最大值时，请执行以下操作

^{pr2}$

这不会创建数组的副本，而是创建两个变量，它们都引用同一数组。因此，对test_term的任何进一步修改实际上都反映在这两个变量引用的列表中。在

由于您在脚本中定义了一个全局级别的test_terms，所以当您进行此调用时，您将对其进行核武处理

def list_scrambler(unscrambled_list):
    test_terms=[]
    countdown = len(unscrambled_list) + 1
    for x in range(1, countdown):
        transfer_var = random.randint(0,len(unscrambled_list)-1)
        test_terms.append(unscrambled_list[transfer_var])
        del unscrambled_list[transfer_var]
    return test_terms

还要补充一下

匈牙利符号是个大禁忌，而python无论如何都是一种强类型语言。如果你很难跟踪时间，不要依赖变量名。取而代之的是给你自己一个IDE或者用一个能表达他们正在做什么的名字。在

if something == false:

应该重写为

if not something

这是一个更多的偏好，但当打印出需要数据浮动的文本时，您可以省去一些头痛和写作

"D) {0}".format(somelist[index]) 

这将把变量填充到{0}中，并为您提供一些格式化上下文，防止您不得不str()对象。在

而且，全局变量通常被认为是一件不好的事情，值得商榷。就像C中的global一样，有时它们的作用是明确的，但在大多数情况下，它们隐藏了bug，使问题更难跟踪。有时你的变量声明会隐藏全局变量，其他的（如你所见）会让你把事情搞砸。在