使用python处理重复结构化的文本文件 [英] Processing repeatedly structured text file with python

问题描述

我有一个大的文本文件，其结构如下:

I have a big text file structured in blocks like:

Student = {
        PInfo = {
                ID   = 0001;
            Name.First = "Joe";
            Name.Last = "Burger";
            DOB  = "01/01/2000";
        };
        School = "West High";
        Address = {
            Str1 = "001 Main St.";
            Zip = 12345;
        };
    };
    Student = {
        PInfo = {
            ID   = 0002;
            Name.First = "John";
            Name.Last = "Smith";
            DOB  = "02/02/2002";
        };
        School = "East High";
        Address = {
            Str1 = "001 40nd St.";
            Zip = 12346;
        };
        Club = "Football";
    };
    ....

Student块共享相同的条目，例如"PInfo"，"School"和"Address"，但是其中一些可能具有其他条目，例如"John Smith"的"Club"信息(不包括在乔·汉堡". 我要做的是获取每个学生的姓名，学校名称和邮政编码，并将它们存储在字典中，例如

The Student blocks share the same entries like "PInfo", "School" and "Address", but some of them may have additional entries, such as the "Club" information for "John Smith" which is not included for "Joe Burger". What I want to do is to get Name, School name and zip code of each student and store them in a dictionary, like

    {'Joe Burger':{School:'West High', Zip:12345}, 'John Smith':{School:'East High', Zip:12346}, ...}

作为python编程的新手，我试图打开文件并逐行分析它，但是它看起来很麻烦.而且实际文件比我上面发布的示例还大且复杂.我想知道是否有更简单的方法来做到这一点.谢谢你.

Being new to python programming, I tried to open the file and analyze it line by line, but it looks so cumbersome. And the real file is quite large and more complicated than the example I posted above. I am wondering if there is an easier way to do it. Thanks ahead.

推荐答案

要解析文件，您可以定义描述输入格式的语法，然后使用该语法生成​​解析器.

To parse the file you could define a grammar that describes your input format and use it to generate a parser.

有许多Python语言解析器.例如，您可以使用 Grako ，该语法采用

There are many language parsers in Python. For example, you could use Grako that takes grammars in a variation of EBNF as input, and outputs memoizing PEG parsers in Python.

要安装Grako，请运行pip install grako.

To install Grako, run pip install grako.

以下是使用Grako的EBNF语法的格式的语法:

Here's grammar for your format using Grako's flavor of EBNF syntax:

(* a file is zero or more records *)
file = { record }* $;
record = name '=' value ';' ;
name = /[A-Z][a-zA-Z0-9.]*/ ;
value = object | integer | string ;
(* an object contains one or more records *)
object = '{' { record }+ '}' ;
integer = /[0-9]+/ ;
string = '"' /[^"]*/ '"';

要生成解析器，请将语法保存到文件中，例如Structured.ebnf并运行:

To generate parser, save the grammar to a file e.g., Structured.ebnf and run:

$ grako -o structured_parser.py Structured.ebnf

它将创建structured_parser模块，该模块可用于从输入中提取学生信息:

It creates structured_parser module that can be used to extract the student information from the input:

#!/usr/bin/env python
from structured_parser import StructuredParser

class Semantics(object):
    def record(self, ast):
        # record = name '=' value ';' ;
        # value = object | integer | string ;
        return ast[0], ast[2] # name, value
    def object(self, ast):
        # object = '{' { record }+ '}' ;
        return dict(ast[1])
    def integer(self, ast):
        # integer = /[0-9]+/ ;
        return int(ast)
    def string(self, ast):
        # string = '"' /[^"]*/ '"';
        return ast[1]

with open('input.txt') as file:
    text = file.read()
parser = StructuredParser()
ast = parser.parse(text, rule_name='file', semantics=Semantics())
students = [value for name, value in ast if name == 'Student']
d = {'{0[Name.First]} {0[Name.Last]}'.format(s['PInfo']):
     dict(School=s['School'], Zip=s['Address']['Zip'])
     for s in students}
from pprint import pprint
pprint(d)

输出

{'Joe Burger': {'School': u'West High', 'Zip': 12345},
 'John Smith': {'School': u'East High', 'Zip': 12346}}

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