Python3 双引号解析与检测答案

【问题标题】：Python3 Double Quote Parsing and DetectionPython3 双引号解析与检测
【发布时间】：2016-12-20 20:54:53
【问题描述】：

我正在尝试检测 .txt 文档中的某些文本字符。

我无法检测到： "" ，但我可以检测到 "。

我正在搜索“quote_test.txt”的假文本

"This is a test of the :: failure";"123";"Joe"
"This test should have failed on the above";"456";"Kathy ::"
"This is also a problem : they say";"789 "" test";"Jim"
"So is a , evidently when in a field";"543 :";"Mary"
"Will have to think about \"\" as a search";",475::";"Sue"
"Which is similar to the issue with " I think";"9463";"Toby"

脚本是：

import csv
import re

fail_text = re.compile('(:|::|,|""|")') # "" is not detected

with open("quote_test.txt") as fp:
    reader = csv.reader(fp, delimiter=';')

    for numx, line in enumerate(reader):
        for numy, column in enumerate(line):          
            m = re.search(fail_text, column)
            if m:
                print('Line {} Column {} has {} in {}'.format(
                    numx, numy, m.group(), column)
                )

输出看起来像这样，没有检测到文本中的“”：

Line 0 Column 0 has : in This is a test of the :: failure
Line 1 Column 2 has : in Kathy ::
Line 2 Column 0 has : in This is also a problem : they say
Line 2 Column 1 has " in 789 " test
Line 3 Column 0 has , in So is a , evidently when in a field
Line 3 Column 1 has : in 543 :
Line 4 Column 0 has " in Will have to think about \\" as a search"
Line 4 Column 1 has , in ,475::
Line 5 Column 0 has " in Which is similar to the issue with  I think"

最初我出于习惯逃避了text like this Stack solution，但没有奏效。

【问题讨论】：

我认为问题在于如何在 re.compile 中处理双引号，因为：fail_text = re.compile('::') 可以找到 :: 但 fail_text = re.compile('""') 没有。
如果你逃避双引号会发生什么？ fail_text = re.compile('(:|::|,|\"\"|")')
re.compile('(:|::|\"\"|,|")') 和这个re.compile('\"\"') - 不接“”
如果您查看输出，您的 RE 不会检测到“::”（双冒号）。如果双双引号或双冒号不重要，则只需使用 fail_text = re.compile('(::?|,|""?)')
为什么你的文字中的双引号被转义了，而所有的单引号都没有？

标签： regex python-3.x text

【解决方案1】：

我可以通过将 csv.reader() 中的转义字符设置为 escapechar='\\' 并将正则表达式更改为 ""? 来解决此问题

def delimiter_check():

    fail_text = re.compile('(::?|This|,|""?)')

    with open("quote_test.txt") as fp:
        reader = csv.reader(fp, delimiter=';', quotechar='"', escapechar='\\')

        for numx, line in enumerate(reader):
            for numy, column in enumerate(line):          
                m = re.search(fail_text, column)
                if m:
                    print('Line {} Column {} has {} in {}'.format(
                        numx, numy, m.group(), column)
                    )

如果文本中的双引号是这样转义的：\"\"，那么脚本应该会找到双引号。

Line 4 Column 0 has "" in Will have to think about "" as a search

【讨论】：