将字符串列表从文件转换为整数列表

Question

我有一个用空格和逗号分隔的整数填充的大文件。我试图一次读取 1KB 并将其转换为整数列表。

这段代码运行良好：

with open('test_age.txt', 'r+') as inf:
    with open('test_age_out.txt', 'r+') as outf:
        sorted_list =[]
        a = [x.strip() for x in inf.read(1000).split(',')]
        int_a = map(int, a)
        f = tempfile.TemporaryFile()
        outf_array = sorted(int_a)
        f.write(str(outf_array))
        f.seek(0)
        #etc...

输出：

[1, 1, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, etc...

但是一旦我添加了一个while循环来读取下一个1KB：

with open('test_age.txt', 'r+') as inf:
    with open('test_age_out.txt', 'r+') as outf:
        sorted_list =[]
        while True:
            a = [x.strip() for x in inf.read(1000).split(',')]
            int_a = map(int, a)
            if not a:
                break
            f = tempfile.TemporaryFile()
            outf_array = sorted(int_a)
            print outf_array
            f.write(str(outf_array))
            f.seek(0)      

我得到了输出和一个 ValueError：

[1, 1, 2, 3, 3, 4, 4, 4, 5, 5, 5, 6, 6, 6, 6, 7, 7, 7, 7, 8, 8, 8, 8, 
8, 9, 9, 9, 10, 10, 10, 10, 10, 10, 10, 10, 10, 11, 11, 11, 12, 12, 12,
12, 12, 12, 13, 13, 13, 14, 14, 14, 14, 14, 14, 14, 15, 15, 16, 17, 18,
19, 19, 20, 20, 20, 20, 21, 21, 22, 22, 22, 23, 23, 24, 24, 24, 24, 25, 
25, 25, 25, 25, 26, 26, 26, 26, 27, 27, 27, 28, 28, 29, 30, 30, 30, 30,
31, 31, 31, 32, 32, 33, 33, 33, 33, 33, 33, 34, 34, 34, 34, 34, 35, 35,
35, 35, 35, 36, 36, 37, 37, 37, 37, 38, 38, 39, 39, 39, 39, 39, 39, 40,
40, 40, 40, 41, 41, 42, 43, 43, 43, 44, 44, 44, 44, 44, 45, 46, 46, 46,
46, 47, 47, 47, 47, 47, 48, 48, 48, 48, 48, 48, 49, 49, 49, 50, 50, 50,
50, 50, 50, 51, 51, 51, 51, 51, 51, 52, 52, 52, 52, 52, 52, 53, 53, 54,
54, 54, 55, 55, 55, 55, 56, 56, 56, 56, 56, 57, 57, 57, 57, 58, 58, 58,
59, 59, 60, 60, 60, 61, 62, 62, 62, 62, 63, 63, 63, 63, 63, 63, 63, 64,
64, 64, 65, 66, 66, 67, 67, 67, 67, 68, 68, 68, 68, 68, 69, 69, 69, 69, 
69, 69, 69, 70, 70, 70, 70, 71, 71, 72, 72, 73, 74, 74, 74, 75, 76, 76,
76, 76, 77, 77, 77, 77, 78, 78, 79, 79, 79, 79, 81, 81, 81, 81, 82, 82, 
82, 82, 82, 83, 83, 83, 83, 84, 85, 85, 85, 85, 86, 86, 86, 87, 87, 87,
87, 87, 87, 88, 88, 88, 88, 88, 88, 88, 89, 89, 89, 89, 90, 90, 90, 91,
91, 91, 91, 91, 91, 91, 92, 92, 93, 93, 93, 94, 94, 94, 94, 95,  95,
96, 96, 96, 97, 97, 98, 99, 100, 100, 100, 100, 100]
[2, 3, 3, 3, 3, 4, 4, 5, 5, 6, 8, 9, 10, 10, 11, 11, 11, 11, 12, 12,12, 
13, 14, 15, 17, 17, 17, 17, 17, 17, 18, 18, 18, 20, 21, 22, 22, 22, 22, 
23, 23, 24, 24, 24, 26, 27, 27, 27, 27, 28, 28, 29, 29, 29, 29, 30, 32, 
32, 32, 32, 33, 33, 34, 34, 36, 37, 37, 37, 37, 38, 39, 41, 41, 42, 43,   
44, 44, 46, 46, 47, 48, 49, 49, 49, 49, 51, 51, 52, 52, 52, 52, 53, 54, 
54, 54, 55, 55, 56, 60, 60, 61, 61, 61, 62, 63, 63, 64, 65, 65, 65, 65, 
66, 66, 67, 68, 68, 68, 70, 70, 73, 73, 73, 74, 74, 75, 75, 75, 77, 77, 
77, 77, 78, 78, 78, 78, 79, 80, 81, 81, 82, 82, 83, 83, 83, 83, 84, 84, 
85, 85, 85, 85, 86, 87, 88, 90, 91, 91, 91, 92, 93, 93, 93, 94, 95, 97, 
98, 98, 99, 100]
    int_a = map(int, a)
ValueError: invalid literal for int() with base 10: ''

我不确定为什么会这样。如果我调用打印，似乎列表正在创建和排序。但是 ValueError 存在。什么给了？

Answer 1

查看str.split 的输出，并在字符串的头部或尾部出现传递的分隔符：

>>> ', 3, 5'.split(', ')
['', '3', '5']

该空字符串是您的程序尝试（但失败）解析为整数的内容。 ''.strip() 没有帮助（顺便说一下，int() 也不需要 - 它会自动忽略前导和尾随空格）。我建议阅读保证完整且有效的块，例如行。如果文件只是一个大行，您将不得不做一些额外的工作来保存一行中的最后一个字符并将它们移动到下一行的处理中。不要忘记在循环之后处理剩余的字符。

line = inf.read(1000)
new += line
current, delimiter, new = line.rpartition(', ')
# process current
# continue loop to add more content

如果文件可以轻松放入系统内存中，您可以读取整个文件并一次性拆分：

numbers = map(int, inf.read().split(', '))