通过截断从文件中删除最终字符

Question

我想在 python 中删除文本文件中的最后一个逗号。该文件如下所示：

{"time":"2019-02-12T14:41:25.2424552+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"GetAlteracion","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531"},"response":null,"status":200},  
{"time":"2019-02-12T14:41:25.5525828+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Expedientes_dmz_","service":"GetObligatoriedadDocumental","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531","tipo_alteracion":"ALT_1","id_expediente":""},"response":null,"status":400},  
{"time":"2019-02-12T14:41:25.9169746+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"Ubicar","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531","epsg":"EPSG:4326"},"response":null,"status":200},
{"time":"2019-02-12T14:41:29.8222248+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"GetAlteracion","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819"},"response":null,"status":200},  
{"time":"2019-02-12T14:41:29.9708861+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Expedientes_dmz_","service":"GetObligatoriedadDocumental","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","tipo_alteracion":"ALT_1","id_expediente":""},"response":null,"status":400} ,  
{"time":"2019-02-12T14:41:30.3077709+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"Ubicar","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","epsg":"EPSG:4326"},"response":null,"status":200},  
{"time":"2019-02-12T14:41:38.7145697+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Documentos_dmz_","service":"obtenerDocumento","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","documento":"E000226847","control":11},"response":null,"status":200},  

我想删除最后一行中的逗号。在看了很多例子之后，我尝试了这段代码（以及很多类似的选项）：

with open('data.txt', 'w') as f:    
    f.seek(f.tell() - 1, os.SEEK_SET)
    f.truncate()

但这不起作用。有什么帮助吗？

编辑

逗号和'}' 之间没有空格。如果文件以逗号结尾，我们办公室中的程序（我无权访问它）会出错。我需要的是只删除文件最后一行中的最后一个逗号，而不是每一行，并以这种方式返回文件：

{"time":"2019-02-12T14:41:25.2424552+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"GetAlteracion","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531"},"response":null,"status":200},  
{"time":"2019-02-12T14:41:25.5525828+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Expedientes_dmz_","service":"GetObligatoriedadDocumental","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531","tipo_alteracion":"ALT_1","id_expediente":""},"response":null,"status":400},  
{"time":"2019-02-12T14:41:25.9169746+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"Ubicar","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531","epsg":"EPSG:4326"},"response":null,"status":200},
{"time":"2019-02-12T14:41:29.8222248+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"GetAlteracion","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819"},"response":null,"status":200},  
{"time":"2019-02-12T14:41:29.9708861+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Expedientes_dmz_","service":"GetObligatoriedadDocumental","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","tipo_alteracion":"ALT_1","id_expediente":""},"response":null,"status":400},  
{"time":"2019-02-12T14:41:30.3077709+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"Ubicar","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","epsg":"EPSG:4326"},"response":null,"status":200},  
{"time":"2019-02-12T14:41:38.7145697+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Documentos_dmz_","service":"obtenerDocumento","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","documento":"E000226847","control":11},"response":null,"status":200}

编辑 2 最后，@holdenweb 解决方案对我有用！ ：

with open('data.txt', 'ab'):
    f.seek(-1, 2)
    f.truncate()

Answer 1

我注意到, 不是您数据中的最后一个符号，这就是您的解决方案以及rstrip(',') 不起作用的原因。请改用replace：

with open('data.txt', 'r') as f:
    data = f.read().replace('} ,', '}')

with open('data.txt', 'w') as f:
    f.write(data)

此脚本删除每行的最后一个逗号（因为'} ,' 仅出现在每行的末尾），您将在输出中获得以下信息：

{"time":"2019-02-12T14:41:25.2424552+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"GetAlteracion","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531"},"response":null,"status":200}
{"time":"2019-02-12T14:41:25.5525828+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Expedientes_dmz_","service":"GetObligatoriedadDocumental","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531","tipo_alteracion":"ALT_1","id_expediente":""},"response":null,"status":400}
{"time":"2019-02-12T14:41:25.9169746+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"Ubicar","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_85531","epsg":"EPSG:4326"},"response":null,"status":200}
{"time":"2019-02-12T14:41:29.8222248+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"GetAlteracion","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819"},"response":null,"status":200}
{"time":"2019-02-12T14:41:29.9708861+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Expedientes_dmz_","service":"GetObligatoriedadDocumental","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","tipo_alteracion":"ALT_1","id_expediente":""},"response":null,"status":400}
{"time":"2019-02-12T14:41:30.3077709+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Alteraciones_Primitivas_dmz_","service":"Ubicar","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","epsg":"EPSG:4326"},"response":null,"status":200}
{"time":"2019-02-12T14:41:38.7145697+01:00","ip":"::1","browser":"Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/72.0.3626.96 Safari/537.36","user":"28969523B","profile":"SUMUM_D?99?2017?2","controller":"Documentos_dmz_","service":"obtenerDocumento","delegacion":null,"municipio":null,"method":"GET","parameters":{"id_alteracion":"11_31_17819","documento":"E000226847","control":11},"response":null,"status":200}

Answer 2

您的代码不起作用，因为以写入模式打开文件会立即将其截断为零长度。您需要追加模式，它将使用任何现有文件的内容。

忽略一个字节等于一个字符的假设（一旦 Unicode 进入图片，情况并非总是如此），并假设文件末尾没有换行符并且您希望保留空间，这应该有效：

with open('data.txt', 'ab'):
    f.seek(-1, 2)
    f.truncate()

Answer 3

此解决方案定位最后一个的索引 } 在最后一行并将字符串替换为索引。

之后可以选择重命名“新”文件。

with open("datain.txt", 'r') as f_in, open('dataout.txt', 'w') as f_out:
    last = None
    for l in f_in.readlines():
        if last:
            f_out.write(last)
        last = l
    i = last.rfind("}")
    f_out.write(last[:i+1])

您也可以这样做，但是我不知道它如何处理编码，并且循环可能会受到更多限制，因此您最终不会截断整个文件。

import os
with open("datain.txt", "r+") as f:
    f.seek(0, os.SEEK_END)
    pos = f.tell()

    while pos > 0:
        f.seek(pos)
        c = f.read(1).encode('utf-8')
        if c == b'}':
            break
        pos = f.tell() - 2
    f.truncate(pos)

Answer 4

这个怎么样。

rf = open('data.txt').read()
with open('data.txt', 'w') as wf:
    wf.write(rf[:-3])

Answer 5

使用这个：

res = your_string.rstrip(',')

为documentation

希望对你有帮助 谢谢