Python Processing Unstructured Data
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小牛编辑
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2023-12-01
已经以行和列格式存在的数据或者可以轻松转换为行和列的数据,以便以后它可以很好地适应数据库,称为结构化数据。 示例包括CSV,TXT,XLS文件等。这些文件具有分隔符和固定宽度或可变宽度,其中缺失值在分隔符之间表示为空白。 但有时我们会得到数据不是固定宽度的数据,或者它们只是HTML,图像或pdf文件。 这种数据称为非结构化数据。 虽然可以通过处理HTML标记来处理HTML文件,但是来自twitter的提要或来自新闻提要的纯文本文档可以在没有分隔符的情况下没有要处理的标记。 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。
阅读数据
在下面的示例中,我们获取一个文本文件并读取隔离其中每一行的文件。 接下来,我们可以将输出分成更多的行和单词。 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,它会产生以下结果。
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.
计算单词频率
我们可以使用计数器功能计算文件中单词的频率,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,它会产生以下结果。
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})