迭代循环中的字符串格式问题

Question

我正在尝试重新格式化一些数据并将其保存到 python 中的输出文件中。我 .strip() 原始的每一行并将其附加到列表中。我创建了第二个列表，其中包含我需要添加到原始数据的值（修改包含原始数据）并在我需要从原始数据列表。输出需要在输出的每条记录中插入一些仅出现一次的信息，因此它不是 1:1 输出（原始行到输出行），我相信这就是我遇到问题的地方。这是我的代码示例...

原始数据：

Client
#ofrecords(as an integer)
Line1ofrecord1
Line2ofrecord1
....
Line1ofrecord2
Line2ofrecord2
....
End

代码：

def shouldbesimple(originalfile):
    inputfile = open(originalfile, "r")
    outputfile = open('finaloutput.txt', "w")
    nowhitespace = originalfile.strip()
    Client = nowhitespace.pop(0)
    Counter = nowhitespace.pop(0)  (each record has exactly the same number of lines)

    #at this point only record information remains in list..

    Header = "stuff at beginning of each record in output"
    Insertclient = "NEEDED {1} CHANGES"
    Line1 = "THINGS I {0} MUST ADD"
    Footer = "stuff at end of each record in output"
    thingstoadd = [Header, Line1, Insertclient, Footer]
    while counter > 0 :
        writetofile = ""
        for element in thingstoadd:
            writetofile = element.format(nowhitespace.pop(0), Client)
            outputfile.write(writetofile + "\n")
        counter = counter - 1
    inputfile.close()
    outputfile.close()

在我开始迭代要添加的东西之前，一切都按预期工作..

数据未按预期排列，我收到“从空列表中弹出”错误。打印 writetofile 显示 python 在每次迭代时都在 format 语句中运行 nowhitespace.pop(0) 操作，而不仅仅是当 {0} 出现在相关元素中时。

有没有更合适的方法将原始信息传递到字符串数据中，或者防止.pop()操作在每个元素上发生？

Answer 1

与其尝试调试您的代码，不如让我向您展示我将如何做我认为您想做的事情。

import itertools

# from itertools recipes in the docs
def grouper(iterable, n, fillvalue=None):
    "Collect data into fixed-length chunks or blocks"
    # grouper('ABCDEFG', 3, 'x') --> ABC DEF Gxx
    args = [iter(iterable)] * n
    return itertools.izip_longest(fillvalue=fillvalue, *args)

def shouldbesimple(originalfile):
    with open(originalfile) as inputfile, open('finaloutput.txt', "w") as outputfile:
        client = next(inputfile).rstrip()
        count = int(next(inputfile).rstrip())
        groups = grouper(inputfile, 4)

        Header = "stuff at beginning of each record in output"
        Insertclient = "NEEDED {1} CHANGES"
        Line1 = "THINGS I {0} MUST ADD"
        Footer = "stuff at end of each record in output"
        thingstoadd = [Header, Line1, Insertclient, Footer]

        for _ in range(count):
            for fmt, line in zip(thingstoadd, next(groups)):
                outputfile.write(fmt.format(line.rstrip(), Client) + '\n')

有了这个输入：

Client
2
Line1ofrecord1
Line2ofrecord1
Line3ofrecord1
Line4ofrecord1
Line1ofrecord2
Line2ofrecord2
Line3ofrecord2
Line4ofrecord2
End

我得到这个输出：

THINGS I Line2ofrecord1 MUST ADD
NEEDED Client CHANGES
stuff at end of each record in output
stuff at beginning of each record in output
THINGS I Line2ofrecord2 MUST ADD
NEEDED Client CHANGES
stuff at end of each record in output