Python中的文本文件解析问题

Question

我是 python 新手，如果我找到单词“Lett”，我会尝试删除文本文件中的行。在行中。这是我试图解析的文本文件的示例：

<A>Lamb</A> <W>Let. Moxon</W>
<A>Lamb</A> <W>Danger Confound. Mor. w. Personal Deformity</W>
<A>Lamb</A> <W>Gentle Giantess</W>
<A>Lamb</A> <W>Lett., to Wordsw.</W>
<A>Lamb</A> <W>Lett., to Procter</W>
<A>Lamb</A> <W>Let. to Old Gentleman</W>
<A>Lamb</A> <W>Elia Ser.</W>
<A>Lamb</A> <W>Let. to T. Manning</W>

我知道如何打开该文件，但我只是不确定如何找到匹配的文本以及如何删除该行。任何帮助将不胜感激。

Answer 1

f = open("myfile.txt", "r")
for line in f:
  if not "Lett." in line: print line,

f.close()

或者如果您想将结果写入文件：

f = open("myfile.txt", "r")
lines = f.readlines()
f.close()
f = open("myfile.txt", "w")
for line in lines:
  if not "Lett." in line: f.write(line)

f.close()

Answer 2

# Open input text
text = open('in.txt', 'r')
# Open a file to output results
out = open('out.txt', 'w')

# Go through file line by line
for line in text.readlines():
    if 'Lett.' not in line: ### This is the crucial line.
        # add line to file if 'Lett.' is not in the line
        out.write(line)
# Close the file to save changes
out.close()

Answer 3

我有一个针对此类内容的通用流编辑器框架。我将文件加载到内存中，将更改应用于内存中的行列表，并在发生更改时写出文件。

我有如下所示的样板：

from sed_util import delete_range, insert_range, append_range, replace_range

def sed(filename):
    modified = 0

    # Load file into memory
    with open(filename) as f:
        lines = [line.rstrip() for line in f]

    # magic here...

    if modified:
        with open(filename, "w") as f:
            for line in lines:
                f.write(line + "\n")

在 # magic here 部分中，我有：

1. 对各行的修改，例如：

   lines[i] = change_line(lines[i])

2. 调用我的 sed 实用程序来插入、追加和替换行，例如：

   lines = delete_range(lines, some_range)

后者使用如下原语：

def delete_range(lines, r):
    """
    >>> a = list(range(10))
    >>> b = delete_range(a, (1, 3))
    >>> b
    [0, 4, 5, 6, 7, 8, 9]
    """
    start, end = r
    assert start <= end
    return [line for i, line in enumerate(lines) if not (start <= i <= end)]

def insert_range(lines, line_no, new_lines):
    """
    >>> a = list(range(10))
    >>> b = list(range(11, 13))
    >>> c = insert_range(a, 3, b)
    >>> c
    [0, 1, 2, 11, 12, 3, 4, 5, 6, 7, 8, 9]
    >>> c = insert_range(a, 0, b)
    >>> c
    [11, 12, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    >>> c = insert_range(a, 9, b)
    >>> c
    [0, 1, 2, 3, 4, 5, 6, 7, 8, 11, 12, 9]
    """
    assert 0 <= line_no < len(lines)
    return lines[0:line_no] + new_lines + lines[line_no:]

def append_range(lines, line_no, new_lines):
    """
    >>> a = list(range(10))
    >>> b = list(range(11, 13))
    >>> c = append_range(a, 3, b)
    >>> c
    [0, 1, 2, 3, 11, 12, 4, 5, 6, 7, 8, 9]
    >>> c = append_range(a, 0, b)
    >>> c
    [0, 11, 12, 1, 2, 3, 4, 5, 6, 7, 8, 9]
    >>> c = append_range(a, 9, b)
    >>> c
    [0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 11, 12]
    """
    assert 0 <= line_no < len(lines)
    return lines[0:line_no+1] + new_lines + lines[line_no+1:]

def replace_range(lines, line_nos, new_lines):
    """
    >>> a = list(range(10))
    >>> b = list(range(11, 13))
    >>> c = replace_range(a, (0, 2), b)
    >>> c
    [11, 12, 2, 3, 4, 5, 6, 7, 8, 9]
    >>> c = replace_range(a, (8, 10), b)
    >>> c
    [0, 1, 2, 3, 4, 5, 6, 7, 11, 12]
    >>> c = replace_range(a, (0, 10), b)
    >>> c
    [11, 12]
    >>> c = replace_range(a, (0, 10), [])
    >>> c
    []
    >>> c = replace_range(a, (0, 9), [])
    >>> c
    [9]
    """
    start, end = line_nos
    return lines[:start] + new_lines + lines[end:]

def find_line(lines, regex):
    for i, line in enumerate(lines):
        if regex.match(line):
            return i

if __name__ == '__main__':
    import doctest
    doctest.testmod()

为了清楚起见，测试适用于整数数组，但转换也适用于字符串数组。

通常，我会扫描行列表来识别要应用的更改（通常使用正则表达式），然后将更改应用于匹配的数据。例如，今天我最终对 150 个文件进行了大约 2000 行更改。

当您需要应用多行模式或附加逻辑来确定更改是否适用时，这比 sed 效果更好。

Answer 4

return [l for l in open(fname) if 'Lett' 不在 l 中]

Answer 5

result = ''
for line in open('in.txt').readlines():
    if 'lett' not in line:
        result += line
f = open('out.txt', 'a')
f.write(result)