📜  Python处理非结构化数据

📅  最后修改于: 2020-12-13 14:16:17             🧑  作者: Mango


已以行和列格式存在的数据,或可以轻松转换为行和列的数据,以便以后可以很好地适合数据库的数据称为结构化数据。例如CSV,TXT,XLS文件等。这些文件具有定界符以及固定宽度或可变宽度,其中缺失值在定界符之间表示为空白。但是有时候我们得到的数据行的宽度不是固定的,或者只是HTML,图像或pdf文件。此类数据称为非结构化数据。尽管可以通过处理HTML标签来处理HTML文件,但是来自Twitter的feed或来自新闻feed的纯文本文档都可以在没有分隔符的情况下处理标签。在这种情况下,我们使用来自各种Python库的不同内置函数来处理文件。

读取数据

在下面的示例中,我们获取一个文本文件,然后读取该文件以分隔其中的每一行。接下来,我们可以将输出分为更多的行和单词。原始文件是一个文本文件,其中包含一些描述Python语言的段落。

filename = 'path\input.txt'  

with open(filename) as fn:  

# Read each line
   ln = fn.readline()

# Keep count of lines
   lncnt = 1
   while ln:
       print("Line {}: {}".format(lncnt, ln.strip()))
       ln = fn.readline()
       lncnt += 1

当我们执行上面的代码时,它产生以下结果。

Line 1: Python is an interpreted high-level programming language for general-purpose programming. Created by Guido van Rossum and first released in 1991, Python has a design philosophy that emphasizes code readability, notably using significant whitespace. It provides constructs that enable clear programming on both small and large scales.
Line 2: Python features a dynamic type system and automatic memory management. It supports multiple programming paradigms, including object-oriented, imperative, functional and procedural, and has a large and comprehensive standard library.
Line 3: Python interpreters are available for many operating systems. CPython, the reference implementation of Python, is open source software and has a community-based development model, as do nearly all of its variant implementations. CPython is managed by the non-profit Python Software Foundation.

计数词频

我们可以使用计数器函数来计算文件中单词的出现频率,如下所示。

from collections import Counter

with open(r'pathinput2.txt') as f:
               p = Counter(f.read().split())
               print(p)

当我们执行上面的代码时,它产生以下结果。

Counter({'and': 3, 'Python': 3, 'that': 2, 'a': 2, 'programming': 2, 'code': 1, '1991,': 1, 'is': 1, 'programming.': 1, 'dynamic': 1, 'an': 1, 'design': 1, 'in': 1, 'high-level': 1, 'management.': 1, 'features': 1, 'readability,': 1, 'van': 1, 'both': 1, 'for': 1, 'Rossum': 1, 'system': 1, 'provides': 1, 'memory': 1, 'has': 1, 'type': 1, 'enable': 1, 'Created': 1, 'philosophy': 1, 'constructs': 1, 'emphasizes': 1, 'general-purpose': 1, 'notably': 1, 'released': 1, 'significant': 1, 'Guido': 1, 'using': 1, 'interpreted': 1, 'by': 1, 'on': 1, 'language': 1, 'whitespace.': 1, 'clear': 1, 'It': 1, 'large': 1, 'small': 1, 'automatic': 1, 'scales.': 1, 'first': 1})