def summarize(title, text, summary_length=5):
"""
Summarizes a single document.
Args:
| title (str) -- the document title
| text (str) -- the document test
| summary_length (int) -- the preferred sentence length of the summary (default=5)
Returns:
| summary (list) -- list of sentences selected for the summary.
Currently uses a modified version of `PyTeaser <https://github.com/xiaoxu193/PyTeaser>`, which is based off of `TextTeaser <https://github.com/MojoJolo/textteaser>`.
"""
summary = []
keys = keywords(text)
title_tokens = tokenize(title)
# Score sentences and use the top selections.
ranks = score(sent_tokenize(text), title_tokens,
keys).most_common(summary_length)
for rank in ranks:
summary.append(rank[0])
return summary
def keywords(text):
"""
Gets the top 10 keywords and their frequency scores
from a document.
Sorts them in descending order by number of occurrences.
"""
from operator import itemgetter # for sorting
text = sub(r'[^\w ]', '', text) # strip special chars
text_with_stops = [x.strip('.').lower() for x in text.split()]
numWords = len(text_with_stops)
text = tokenize(text)
freq = Counter()
for word in text:
freq[word] += 1
minSize = min(10, len(freq))
keywords = tuple(freq.most_common(minSize)) # get first 10
keywords = dict((x, y) for x, y in keywords) # recreate a dict
for k in keywords:
articleScore = keywords[k] * 1.0 / numWords
keywords[k] = articleScore * 1.5 + 1
keywords = sorted(iter(keywords.items()), key=itemgetter(1))
keywords.reverse()
return dict(keywords)
def score(sentences, title_words, keywords):
"""
Score sentences based on their features.
Args:
| sentences (list) -- list of sentences to score
| title_words (list) -- list of words in the title
| keywords (list) -- list of keywords from the document
"""
num_sentences = len(sentences)
ranks = Counter()
for i, s in enumerate(sentences):
sentence = tokenize(s)
# Calculate features.
title_score = score_title(title_words, sentence)
s_length = sentence_length(sentence)
s_position = sentence_position(i + 1, num_sentences)
sbs_feature = sbs(sentence, keywords)
dbs_feature = dbs(sentence, keywords)
frequency = (sbs_feature + dbs_feature) / 2.0 * 10.0
# Weighted average of feature scores.
total_score = (title_score * 1.5 + frequency * 2.0 + s_length * 1.0 +
s_position * 1.0) / 4.0
ranks[s] = total_score
return ranks
def keywords(text):
"""
Gets the top 10 keywords and their frequency scores
from a document.
Sorts them in descending order by number of occurrences.
"""
from operator import itemgetter # for sorting
text = sub(r'[^\w ]', '', text) # strip special chars
text_with_stops = [x.strip('.').lower() for x in text.split()]
numWords = len(text_with_stops)
text = tokenize(text)
freq = Counter()
for word in text:
freq[word] += 1
minSize = min(10, len(freq))
keywords = tuple(freq.most_common(minSize)) # get first 10
keywords = dict((x, y) for x, y in keywords) # recreate a dict
for k in keywords:
articleScore = keywords[k]*1.0 / numWords
keywords[k] = articleScore * 1.5 + 1
keywords = sorted(iter(keywords.items()), key=itemgetter(1))
keywords.reverse()
return dict(keywords)
def score(sentences, title_words, keywords):
"""
Score sentences based on their features.
Args:
| sentences (list) -- list of sentences to score
| title_words (list) -- list of words in the title
| keywords (list) -- list of keywords from the document
"""
num_sentences = len(sentences)
ranks = Counter()
for i, s in enumerate(sentences):
sentence = tokenize(s)
# Calculate features.
title_score = score_title(title_words, sentence)
s_length = sentence_length(sentence)
s_position = sentence_position(i+1, num_sentences)
sbs_feature = sbs(sentence, keywords)
dbs_feature = dbs(sentence, keywords)
frequency = (sbs_feature + dbs_feature) / 2.0 * 10.0
# Weighted average of feature scores.
total_score = (title_score*1.5 + frequency*2.0 +
s_length*1.0 + s_position*1.0) / 4.0
ranks[s] = total_score
return ranks
def summarize(title, text, summary_length=5):
"""
Summarizes a single document.
Args:
| title (str) -- the document title
| text (str) -- the document test
| summary_length (int) -- the preferred sentence length of the summary (default=5)
Returns:
| summary (list) -- list of sentences selected for the summary.
Currently uses a modified version of `PyTeaser <https://github.com/xiaoxu193/PyTeaser>`, which is based off of `TextTeaser <https://github.com/MojoJolo/textteaser>`.
"""
summary = []
keys = keywords(text)
title_tokens = tokenize(title)
# Score sentences and use the top selections.
ranks = score(sent_tokenize(text), title_tokens, keys).most_common(summary_length)
for rank in ranks:
summary.append(rank[0])
return summary
def multisummarize(docs, summary_length=5):
"""
Summarize multi documents.
Args:
| docs (list) -- list of documents (i.e. texts)
| summary_length (int) -- the preferred sentence length of the summary (default=5)
.. note::
The current implementation is super naive,
thus the quality and coherence of its summaries is pretty damn terrible.
But it's purpose for now is that there is *some* API for
multidoc summarization.
Returns:
| summary (list) -- list of sentences selected for the summary.
.. note::
BTW: this is super slow. takes well over a minute for 4 moderately-sized documents.
"""
# Collect all sentences from the input documents.
# Also collect position information about each sentence.
sents = []
for doc in docs:
sents += [(sent, vectorize(sent), pos + 1)
for pos, sent in enumerate(sent_tokenize(doc))]
clusters = []
# Cluster the sentences.
for sent in sents:
# sent = (sent, vec, pos)
# Keep track of the maximum scoring cluster
# (above some minimum similarity)
# and the avg sim score.
# The higher the min_sim,
# the harder it is to join a cluster.
min_sim = 0.2
max_cluster = None, min_sim
for cluster in clusters:
avg_sim = 0
for sent_c in cluster:
avg_sim += (1 - cosine(sent[1], sent_c[1]))
avg_sim = avg_sim / len(cluster)
if avg_sim >= max_cluster[1]:
max_cluster = cluster, avg_sim
# If a cluster was found,
# add the sentence to it
if max_cluster[0]:
max_cluster[0].append(sent)
# Otherwise, create a new cluster.
else:
clusters.append([sent])
# Rank the clusters.
# Assuming that clusters with more sentences are more important,
# take the top 5.
ranked_clusters = sorted(clusters, key=lambda x: -len(x))[:summary_length]
# For each sentence cluster, select the highest scoring sentence.
# Again - very naive.
ideal_length = 20
summary_sentences = []
for cluster in ranked_clusters:
max_sent = '', 0
for sent in cluster:
avg_sim = 0
for sent_c in cluster:
avg_sim += 1 - cosine(sent[1], sent_c[1])
avg_sim = avg_sim / len(cluster)
pos = sent[2]
length = fabs(ideal_length - len(tokenize(sent[0]))) / ideal_length
# Score is the average similarity penalized by distance from ideal length,
# weighted by the inverse of the position.
score = (avg_sim - length / 2) / pos
if score >= max_sent[1]:
max_sent = sent[0], score
summary_sentences.append(max_sent[0])
return summary_sentences
def multisummarize(docs, summary_length=5):
"""
Summarize multi documents.
Args:
| docs (list) -- list of documents (i.e. texts)
| summary_length (int) -- the preferred sentence length of the summary (default=5)
.. note::
The current implementation is super naive,
thus the quality and coherence of its summaries is pretty damn terrible.
But it's purpose for now is that there is *some* API for
multidoc summarization.
Returns:
| summary (list) -- list of sentences selected for the summary.
.. note::
BTW: this is super slow. takes well over a minute for 4 moderately-sized documents.
"""
# Collect all sentences from the input documents.
# Also collect position information about each sentence.
sents = []
for doc in docs:
sents += [(sent, vectorize(sent), pos + 1) for pos, sent in enumerate(sent_tokenize(doc))]
clusters = []
# Cluster the sentences.
for sent in sents:
# sent = (sent, vec, pos)
# Keep track of the maximum scoring cluster
# (above some minimum similarity)
# and the avg sim score.
# The higher the min_sim,
# the harder it is to join a cluster.
min_sim = 0.2
max_cluster = None, min_sim
for cluster in clusters:
avg_sim = 0
for sent_c in cluster:
avg_sim += (1 - cosine(sent[1], sent_c[1]))
avg_sim = avg_sim/len(cluster)
if avg_sim >= max_cluster[1]:
max_cluster = cluster, avg_sim
# If a cluster was found,
# add the sentence to it
if max_cluster[0]:
max_cluster[0].append(sent)
# Otherwise, create a new cluster.
else:
clusters.append([sent])
# Rank the clusters.
# Assuming that clusters with more sentences are more important,
# take the top 5.
ranked_clusters = sorted(clusters, key=lambda x: -len(x))[:summary_length]
# For each sentence cluster, select the highest scoring sentence.
# Again - very naive.
ideal_length = 20
summary_sentences = []
for cluster in ranked_clusters:
max_sent = '', 0
for sent in cluster:
avg_sim = 0
for sent_c in cluster:
avg_sim += 1 - cosine(sent[1], sent_c[1])
avg_sim = avg_sim/len(cluster)
pos = sent[2]
length = fabs(ideal_length - len(tokenize(sent[0])))/ideal_length
# Score is the average similarity penalized by distance from ideal length,
# weighted by the inverse of the position.
score = (avg_sim - length/2)/pos
if score >= max_sent[1]:
max_sent = sent[0], score
summary_sentences.append(max_sent[0])
return summary_sentences
