如何在Python中获得一个字符串与另一个字符串相似的概率?

我想要得到一个十进制值,比如0.9(意思是90%)等等。最好是标准的Python和库。

e.g.

similar("Apple","Appel") #would have a high prob.

similar("Apple","Mango") #would have a lower prob.

当前回答

你可以创建这样一个函数:

def similar(w1, w2):
    w1 = w1 + ' ' * (len(w2) - len(w1))
    w2 = w2 + ' ' * (len(w1) - len(w2))
    return sum(1 if i == j else 0 for i, j in zip(w1, w2)) / float(len(w1))

其他回答

Textdistance:

TextDistance - python库,用于通过多种算法比较两个或多个序列之间的距离。它有Textdistance

30 +算法 纯python实现 简单的使用 两个以上的序列比较 有些算法在一个类中有多个实现。 可选的numpy使用最高速度。

例二:

import textdistance
textdistance.hamming('test', 'text')

输出:

1

Example2:

import textdistance

textdistance.hamming.normalized_similarity('test', 'text')

输出:

0.75

谢谢,干杯!

还添加了Spacy NLP库;

@profile
def main():
    str1= "Mar 31 09:08:41  The world is beautiful"
    str2= "Mar 31 19:08:42  Beautiful is the world"
    print("NLP Similarity=",nlp(str1).similarity(nlp(str2)))
    print("Diff lib similarity",SequenceMatcher(None, str1, str2).ratio()) 
    print("Jellyfish lib similarity",jellyfish.jaro_distance(str1, str2))

if __name__ == '__main__':

    #python3 -m spacy download en_core_web_sm
    #nlp = spacy.load("en_core_web_sm")
    nlp = spacy.load("en_core_web_md")
    main()

使用Robert Kern的line_profiler运行

kernprof -l -v ./python/loganalysis/testspacy.py

NLP Similarity= 0.9999999821467294
Diff lib similarity 0.5897435897435898
Jellyfish lib similarity 0.8561253561253562

然而,时间的启示

Function: main at line 32

Line #      Hits         Time  Per Hit   % Time  Line Contents
==============================================================
    32                                           @profile
    33                                           def main():
    34         1          1.0      1.0      0.0      str1= "Mar 31 09:08:41  The world is beautiful"
    35         1          0.0      0.0      0.0      str2= "Mar 31 19:08:42  Beautiful is the world"
    36         1      43248.0  43248.0     99.1      print("NLP Similarity=",nlp(str1).similarity(nlp(str2)))
    37         1        375.0    375.0      0.9      print("Diff lib similarity",SequenceMatcher(None, str1, str2).ratio()) 
    38         1         30.0     30.0      0.1      print("Jellyfish lib similarity",jellyfish.jaro_distance(str1, str2))

你可以在这个链接下找到大多数文本相似度方法及其计算方法:https://github.com/luozhouyang/python-string-similarity#python-string-similarity 这里有一些例子;

归一化,度量,相似度和距离 (归一化)相似度和距离 距离度量 基于相似度和距离的带状(n-gram) Levenshtein 规范化Levenshtein 加权Levenshtein Damerau-Levenshtein 最佳字符串对齐 Jaro-Winkler 最长公共子序列 度量最长公共子序列 语法 基于瓦(n-gram)的算法 Q-Gram 余弦相似度 Jaccard指数 Sorensen-Dice系数 重叠系数(即Szymkiewicz-Simpson)

注意,difflib。SequenceMatcher只找到最长的连续匹配子序列,这通常不是我们想要的,例如:

>>> a1 = "Apple"
>>> a2 = "Appel"
>>> a1 *= 50
>>> a2 *= 50
>>> SequenceMatcher(None, a1, a2).ratio()
0.012  # very low
>>> SequenceMatcher(None, a1, a2).get_matching_blocks()
[Match(a=0, b=0, size=3), Match(a=250, b=250, size=0)]  # only the first block is recorded

寻找两个字符串之间的相似性与生物信息学中成对序列比对的概念密切相关。有许多专门的库,包括生物马拉松。这个例子实现了Needleman Wunsch算法:

>>> from Bio.Align import PairwiseAligner
>>> aligner = PairwiseAligner()
>>> aligner.score(a1, a2)
200.0
>>> aligner.algorithm
'Needleman-Wunsch'

使用biopython或其他生物信息学包比python标准库的任何部分都更灵活,因为有许多不同的评分方案和算法可用。此外,你可以得到匹配的序列来可视化正在发生的事情:

>>> alignment = next(aligner.align(a1, a2))
>>> alignment.score
200.0
>>> print(alignment)
Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-Apple-
|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-|||-|-
App-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-elApp-el

BLEUscore

BLEU,即双语评估替补,是一个用于比较的分数 文本到一个或多个参考译文的候选翻译。 完全匹配的结果是1.0,而完全不匹配的结果是1.0 结果得分为0.0。 虽然它是为翻译而开发的,但也可以用来评估文本 为一套自然语言处理任务生成。

代码:

import nltk
from nltk.translate import bleu
from nltk.translate.bleu_score import SmoothingFunction
smoothie = SmoothingFunction().method4

C1='Text'
C2='Best'

print('BLEUscore:',bleu([C1], C2, smoothing_function=smoothie))

示例:通过更新C1和C2。

C1='Test' C2='Test'

BLEUscore: 1.0

C1='Test' C2='Best'

BLEUscore: 0.2326589746035907

C1='Test' C2='Text'

BLEUscore: 0.2866227639866161

你也可以比较句子的相似度:

C1='It is tough.' C2='It is rough.'

BLEUscore: 0.7348889200874658

C1='It is tough.' C2='It is tough.'

BLEUscore: 1.0