Question

假设我有一个包含以下内容的文本文件

fdsjhgjhg
fdshkjhk
Start
Good Morning
Hello World
End
dashjkhjk
dsfjkhk

现在我需要编写一个Python代码来读取文本文件并将内容复制到Start和end之间。

我写了以下代码。

inFile = open("data.txt")
outFile = open("result.txt", "w")
buffer = []
keepCurrentSet = True
for line in inFile:
    buffer.append(line)
    if line.startswith("Start"):
        #---- starts a new data set
        if keepCurrentSet:
            outFile.write("".join(buffer))
        #now reset our state
        keepCurrentSet = False
        buffer = []
    elif line.startswith("End"):
        keepCurrentSet = True
inFile.close()
outFile.close()

我没有按预期获得所需的输出我刚刚开始我想得到的是开始和结束之间的所有界限。不包括Start＆amp;端。

Answer 1

万一你的文本文件中有多个“开始”和“结束”，这将导入所有数据，不包括所有“开始”和“结束”。

with open('path/to/input') as infile, open('path/to/output', 'w') as outfile:
    copy = False
    for line in infile:
        if line.strip() == "Start":
            copy = True
            continue
        elif line.strip() == "End":
            copy = False
            continue
        elif copy:
            outfile.write(line)

Answer 2

如果文本文件不一定很大，您可以获取文件的全部内容，然后使用正则表达式：

import re
with open('data.txt') as myfile:
    content = myfile.read()

text = re.search(r'Start\n.*?End', content, re.DOTALL).group()
with open("result.txt", "w") as myfile2:
    myfile2.write(text)

Answer 3

使用itertools.dropwhile，itertools.takewhile，itertools.islice：

import itertools

with open('data.txt') as f, open('result.txt', 'w') as fout:
    it = itertools.dropwhile(lambda line: line.strip() != 'Start', f)
    it = itertools.islice(it, 1, None)
    it = itertools.takewhile(lambda line: line.strip() != 'End', it)
    fout.writelines(it)

更新：正如inspectorG4dget所述，上面的代码复制了第一个块。要复制多个块，请使用以下命令：

import itertools

with open('data.txt', 'r') as f, open('result.txt', 'w') as fout:
    while True:
        it = itertools.dropwhile(lambda line: line.strip() != 'Start', f)
        if next(it, None) is None: break
        fout.writelines(itertools.takewhile(lambda line: line.strip() != 'End', it))

Answer 4

我不是Python专家，但这段代码应该可以胜任。

inFile = open("data.txt")
outFile = open("result.txt", "w")
keepCurrentSet = False
for line in inFile:
    if line.startswith("End"):
        keepCurrentSet = False

    if keepCurrentSet:
        outFile.write(line)

    if line.startswith("Start"):
        keepCurrentSet = True
inFile.close()
outFile.close()

Answer 5

将outFile.write电话移至第二个if：

inFile = open("data.txt")
outFile = open("result.txt", "w")
buffer = []
for line in inFile:
    if line.startswith("Start"):
        buffer = ['']
    elif line.startswith("End"):
        outFile.write("".join(buffer))
        buffer = []
    elif buffer:
        buffer.append(line)
inFile.close()
outFile.close()

Answer 6

import re

inFile = open("data.txt")
outFile = open("result.txt", "w")
buffer1 = ""
keepCurrentSet = True
for line in inFile:
    buffer1=buffer1+(line)

buffer1=re.findall(r"(?<=Start) (.*?) (?=End)", buffer1)  
outFile.write("".join(buffer1))  
inFile.close()
outFile.close()

Answer 7

我会这样处理：

inFile = open("data.txt")
outFile = open("result.txt", "w")

data = inFile.readlines()

outFile.write("".join(data[data.index('Start\n')+1:data.index('End\n')]))
inFile.close()
outFile.close()

Answer 8

如果要在提取两个字符串之间的行时保留开始和结束行/关键字。

请在下面找到我用来从 shell 脚本中提取 sql 语句的代码片段

def process_lines(in_filename, out_filename, start_kw, end_kw):
    try:
        inp = open(in_filename, 'r', encoding='utf-8', errors='ignore')
        out = open(out_filename, 'w+', encoding='utf-8', errors='ignore')
    except FileNotFoundError as err:
        print(f"File {in_filename} not found", err)
        raise
    except OSError as err:
        print(f"OS error occurred trying to open {in_filename}", err)
        raise
    except Exception as err:
        print(f"Unexpected error opening {in_filename} is",  repr(err))
        raise
    else:
        with inp, out:
            copy = False
            for line in inp:
                # first IF block to handle if the start and end on same line
                if line.lstrip().lower().startswith(start_kw) and line.rstrip().endswith(end_kw):
                    copy = True
                    if copy:  # keep the starts with keyword
                        out.write(line)
                    copy = False
                    continue
                elif line.lstrip().lower().startswith(start_kw):
                    copy = True
                    if copy:  # keep the starts with keyword
                        out.write(line)
                    continue
                elif line.rstrip().endswith(end_kw):
                    if copy:  # keep the ends with keyword
                        out.write(line)
                    copy = False
                    continue
                elif copy:
                    # write
                    out.write(line)


if __name__ == '__main__':
    infile = "/Users/testuser/Downloads/testdir/BTEQ_TEST.sh"
    outfile = f"{infile}.sql"
    statement_start_list = ['database', 'create', 'insert', 'delete', 'update', 'merge', 'delete']
    statement_end = ";"
    process_lines(infile, outfile, tuple(statement_start_list), statement_end)

使用python在文本文件中提取两个字符串之间的值

8 个答案: