问题
Consider the dataframe like below
df = pd.DataFrame({'Questions': ['What are you doing?','What are you doing tonight?','What are you doing now?','What is your name?','What is your nick name?','What is your full name?','Shall we meet?',
'How are you doing?' ]})
Questions
0 What are you doing?
1 What are you doing tonight?
2 What are you doing now?
3 What is your name?
4 What is your nick name?
5 What is your full name?
6 Shall we meet?
7 How are you doing?
How to group the dataframe with similar Questions? i.e how to get groups like below
for _, i in df.groupby('similarity')['Questions']:
print(i,'\n')
6 Shall we meet? Name: Questions, dtype: object 3 What is your name? 4 What is your nick name? 5 What is your full name? Name: Questions, dtype: object 0 What are you doing? 1 What are you doing tonight? 2 What are you doing now? 7 How are you doing? Name: Questions, dtype: object
A similar question was asked here but with less clarity so no aswers for that question
回答1:
Here's one pretty big approach by finding the normalized similarity score between all the elements in the series and then grouping them by the newly obtained similarity list converted to string. i.e
import numpy as np
import nltk
from nltk.corpus import wordnet as wn
import pandas as pd
def convert_tag(tag):
tag_dict = {'N': 'n', 'J': 'a', 'R': 'r', 'V': 'v'}
try:
return tag_dict[tag[0]]
except KeyError:
return None
def doc_to_synsets(doc):
"""
Returns a list of synsets in document.
Tokenizes and tags the words in the document doc.
Then finds the first synset for each word/tag combination.
If a synset is not found for that combination it is skipped.
Args:
doc: string to be converted
Returns:
list of synsets
Example:
doc_to_synsets('Fish are nvqjp friends.')
Out: [Synset('fish.n.01'), Synset('be.v.01'),
Synset('friend.n.01')]
"""
synsetlist =[]
tokens=nltk.word_tokenize(doc)
pos=nltk.pos_tag(tokens)
for tup in pos:
try:
synsetlist.append(wn.synsets(tup[0], convert_tag(tup[1]))[0])
except:
continue
return synsetlist
def similarity_score(s1, s2):
"""
Calculate the normalized similarity score of s1 onto s2
For each synset in s1, finds the synset in s2 with the largest similarity value.
Sum of all of the largest similarity values and normalize this value by dividing it by the number of largest similarity values found.
Args:
s1, s2: list of synsets from doc_to_synsets
Returns:
normalized similarity score of s1 onto s2
Example:
synsets1 = doc_to_synsets('I like cats')
synsets2 = doc_to_synsets('I like dogs')
similarity_score(synsets1, synsets2)
Out: 0.73333333333333339
"""
highscores = []
for synset1 in s1:
highest_yet=0
for synset2 in s2:
try:
simscore=synset1.path_similarity(synset2)
if simscore>highest_yet:
highest_yet=simscore
except:
continue
if highest_yet>0:
highscores.append(highest_yet)
return sum(highscores)/len(highscores) if len(highscores) > 0 else 0
def document_path_similarity(doc1, doc2):
synsets1 = doc_to_synsets(doc1)
synsets2 = doc_to_synsets(doc2)
return (similarity_score(synsets1, synsets2) + similarity_score(synsets2, synsets1)) / 2
def similarity(x,df):
sim_score = []
for i in df['Questions']:
sim_score.append(document_path_similarity(x,i))
return sim_score
From the above methods defined we can now do
df['similarity'] = df['Questions'].apply(lambda x : similarity(x,df)).astype(str)
for _, i in df.groupby('similarity')['Questions']:
print(i,'\n')
Output :
6 Shall we meet? Name: Questions, dtype: object 3 What is your name? 4 What is your nick name? 5 What is your full name? Name: Questions, dtype: object 0 What are you doing? 1 What are you doing tonight? 2 What are you doing now? 7 How are you doing? Name: Questions, dtype: object
This isn't the best approach to the problem, and is really slow. Any new approach is highly appreciated.
回答2:
You should sort all the names in the list/dataframe column first and then run the similarity code for only for n-1 rows i.e. for every row, compare it with the next element. if the two are similar, you can categorize them as 1 or else 0 and parse through the list. instead of comparing each row with every other element which is n^2.
来源：https://stackoverflow.com/questions/47159996/how-to-group-text-data-based-on-document-similarity