Question

我刚刚开始学习Python（我的第一次涉及编码），这是我第一次发帖...我希望我不会通过提出这个问题来滥用论坛（我实际上是在请专家来帮我学习）。如果这在社区中不受欢迎，请告诉我。

对于密歇根州开放课程的这项任务，我已被指示要求用户输入，直到用户输入“完成”，此时代码应计算最大，最小，总和和平均值。在我的所有测试中，它都运行良好。但我觉得编写这段代码的方式可能要简单得多。有人可以提出改进建议吗？

largest = None
smallest = None
count = 0
sum = 0
while True:
    try:
        num = raw_input("Enter a number: ")
        if num == "done" : break
        num = float(num)
        count = count + 1
        sum = sum + num
        avg = sum/count
        if largest is None:
            largest = num
        if smallest is None:
            smallest = num
        if num < smallest:
            smallest = num
        elif num > largest:
            largest = num
        continue
    except: print 'Invalid input'

print "Maximum is", int(largest)
print "Minimum is", int(smallest)
print "Count:", int(count)
print "Sum:", int(sum)
print "Average:", avg

Answer 1

这里有一些事情：

你可以删除continue语句，因为它仍然是循环的结束;
您可以将if语句压缩为if largest is None or num > largest:这将 shortcircuit 并使循环更小;
您可以使用x += y代替x = x + y;和
您不必计算循环中的内部;在循环结束时计算一次就足够了。

所以：

largest = None smallest = None count = 0 sum = 0 while True: try: num = raw_input("Enter a number: ") if num == "done" : break num = float(num) count += 1 sum += num if largest is None or num > largest: largest = num if smallest is None or num < smallest: smallest = num except: print 'Invalid input' print "Maximum is", int(largest) print "Minimum is", int(smallest) print "Count:", int(count) print "Sum:", int(sum) print "Average:", sum/count

但就大哦而言，你无法提高太多：计算总和等只需要 O（n），它也需要花费 O（ n）无论如何都要读取输入。

此外，一些软件工程建议：不使用一揽子例外，始终指定您期望的例外：

largest = None smallest = None count = 0 sum = 0 while True: try: num = raw_input("Enter a number: ") if num == "done" : break num = float(num) count += 1 sum += num if largest is None or num > largest: largest = num if smallest is None or num < smallest: smallest = num except ValueError: print 'Invalid input' print "Maximum is", int(largest) print "Minimum is", int(smallest) print "Count:", int(count) print "Sum:", int(sum) print "Average:", sum/count

Answer 2

实现此目的的另一种方法是将所有输入存储在列表中，然后使用内置插件min()，max()，len()和sum()找到价值观：

num=raw_input("Enter a number: ")
nums=[]
while num!="done":       #check if user has finished entering inputs
    try:
        nums.append(int(num))       #append the input as an integer to a list
        num=raw_input("Enter a number: ")   #get another input
    except ValueError:
        print "Invalid input"

print "Maximum is",max(nums)
print "Minimum is",min(nums)
print "Count:",len(nums)
print "Sum: ",sum(nums)
print "Average: ",sum(nums)/len(nums)

输出：

Enter a number: 1
Enter a number: 2
Enter a number: 3
Enter a number: 4
Enter a number: 5
Enter a number: 6
Enter a number: done
Maximum is 6
Minimum is 1
Count: 6
Sum:  21
Average:  3.5

如何才能提高此Python代码的效率？

2 个答案: