Question

我有以下输入文件结构，每行都有文字：

line1
line2
line3
line3
line4
line5
line6

当两条线完全相同，即第3行时，我想保留第二条线，并将第一条线的内容更改为＆＃34; SECTION MISSING＆＃34;。我无法将它放在正确的位置。我得到的最接近的是下面的代码，但我得到的输出是：

line1
line2
line3
SECTION MISSING
line4
etc.

虽然我想：

line1
line2
SECTION MISSING
line3 
line4

代码：

def uniq(iterator):
    previous = float("NaN")  # Not equal to anything
    section=("SECTION : MISSING\n")
    for value in iterator:
        if previous == value:
            yield section
        else:
            yield value
            previous = value
    return;

 with open('infile.txt','r') as file:
    with open('outfile.txt','w') as f:
        for line in uniq(file):
            f.write(line)

Answer 1

我认为您想要获得previous，而不是value：

def uniq(iterator):
    previous = None
    section = ("SECTION : MISSING\n")
    for value in iterator:
        if previous == value:
            yield section
        elif previous is not None:
            yield previous
        previous = value
    if previous is not None:
        yield previous

使用示例：

>>> list(uniq([1, 2, 2, 3, 4, 5, 6, 6]))
[1, 'SECTION : MISSING\n', 2, 3, 4, 5, 'SECTION : MISSING\n', 6]

Answer 2

类似的东西：

prev = None
with open('infile.txt','r') as fi:
    with open('outfile.txt','w') as fo:
        for line in fi:
            if prev is not None: 
                fo.write(prev if prev != line else "SECTION : MISSING\n")
            prev = line
        fo.write(prev)

将为您提供您正在寻找的输出文件：

line1
line2
SECTION : MISSING
line3
line4
line5
line6

Answer 3

对于像这样的任务的个人偏好，我使用两个游标而不是一个：

from itertools import tee, izip
with open(infile) as r, open(outfile, 'w') as w:
    p, c = tee(r)
    w.write(next(c))
    for prev,cur in izip(p,c):
        w.write(cur if prev!=cur else 'SECTION : MISSING\n')

Answer 4

如果您必须使用三个连续行（两个或更多个）来处理这种情况，您只想替换第一个，您可以使用groupby：< / p>

from itertools import groupby, islice, chain

def detect_missing(source):
    grouped = groupby(source)
    section = "SECTION: MISSING\n"
    for _, group in grouped:
        first_two = list(islice(group, 2))
        if len(first_two) > 1:
            first_two[0] = section
        yield from chain(first_two, group)

（Python 3，但如果需要，可以删除yield from。）

识别两条连续的相同线并替换第一条线

4 个答案: