python - 如何选择偶数和奇数整数并求和

好吧，我开始新鲜，我将承担我拥有的一切。

NumbersMake.py

#This program writes 1 line of 12 random integers, each in the
#range from 1-100 to a text file.

def main():

    import random

    #Open a file named numbers.txt.
    outfile = open('numbers.txt', 'w')

    #Produce the numbers
    for count in range(12):
        #Get a random number.
        num = random.randint(1, 100)

        #Write 12 random intergers in the range of 1-100 on one line
        #to the file.
        outfile.write(str(num) + " ")

    #Close the file.
    outfile.close()
    print('Data written to numbers.txt')

#Call the main function
main()

上面的代码生成一个文本文件，其中包含：

60 90 75 94 54 12 10 45 60 92 47 65

上面的数字是12个随机产生的整数，中间用空格隔开。

如果删除空格，在第二个脚本中会更容易吗？

NumbersRead.py

#This program reads 12 random integers, outputs each number
#to its own line and then outputs the total of the even and odd  intergers.

def main():

    #Open a file named numbers.txt.
    infile = open('numbers.txt', 'r')

    #Read/process the file's contents.
    file_contents = infile.readline()
    numbers = file_contents.split(" ")
    odd = 0
    even = 0
    num = int(file_contents)
    for file_contents in numbers:
        if num%2 == 0:
            even += num
        else:
            odd += num

    #Close the file.
    infile.close()

    #Print out integer totals
    print('The total of the even intergers is: ', even)
    print('The total of the odd intergers is: ', odd)

#Call the main function
main()

我从上面的脚本中收到的尝试处理偶数和奇数总数的错误是：

Traceback (most recent call last):
  File "numbersread.py", line 29, in <module>
    main()
  File "numbersread.py", line 14, in main
    num = int(file_contents)
ValueError: invalid literal for int() with base 10: '60 90 75 94 54 12 10 45 60 92 47 65 '

我不知道我在做什么错。

最佳答案

假设您有一个类似["1","2","3"...]的列表

odd = sum(int(x) for x in  numbers if x % 2)
even = sum(int(x) for x in  numbers if not x % 2)

最好的方法是使用with打开文件并首先映射到int：

with open('numbers.txt') as f: # closes you files automatically
    numbers = map(int,f.read().split())


    odd = sum(x for x in numbers if x % 2)
    even = sum(x for x in numbers if not x % 2)

如果文件很大，则需要遍历每一行并进行累加。

另外，如果只希望第一行将readline替换为f.read().split()，则仅使用f.readline().split()读取一行

sum(x for x in numbers if x % 2)是generator expression，当对生成器对象调用next（）方法时，对生成器表达式中使用的变量进行延迟计算

关于python - 如何选择偶数和奇数整数并求和，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/28888631/