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摘要: 近年来,细粒度情感分析因其在商业决策、舆情分析等领域的重要作用而受到学术界和工业界的广泛关注.评价对象抽取作为情感分析的基本任务之一,是进行细粒度情感分析的关键问题.本文针对评价对象抽取问题的起源、当前主流研究方法和趋势进行了梳理,首先详细阐述评价对象抽取问题的基本概念并对其进行形式化表示,然后结合近年来的研究对评价对象抽取方法进行归纳和总结,并重点分析基于频率、基于模板规则、基于图论、基于条件随机场和基于深度学习的评价对象抽取方法,随后回顾评价对象抽取的评测情况和可用的语料资源,最后分析评价对象抽取的若干难点问题,同时对评价对象抽取研究进展和发展趋势进行总结和展望.Abstract: In recent years, fine-grained sentiment analysis has received extensive attention from academia and industry for its important role in business decision-making and public opinion analysis. Opinion target extraction, as one of the basic tasks of sentiment analysis, has been the crux of fine-grained sentiment analysis for years. In this paper, the origins, state of the art, and research directions of opinion target extraction are discussed. We first elaborate the basic concepts of opinion target extraction and formalize the problem, and then based on recent literature, we conclude and summarize the approaches and techniques, which we divide into five categories:frequency-based method, pattern-based method, graph-based method, CRF-based method and deep learning based method. We also review several evaluation contests and collect the available corpus resources on opinion target extraction. At the end, the challenges arisen in opinion target extraction are analyzed as well as the probable future is given.1) 本文责任编委 赵铁军
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表 1 基于频率的抽取方法比较
Table 1 Comparison of frequency-based extraction methods
文献 方法 级别 数据集 语言 实验结果1 文献[3]Hu等2004 关联规则挖掘频繁项集+剪枝+根据评价词获取非频繁评价对象 语料 Digital Camera 1 English 0.747 0.822 0.783 Digital Camera 2 English 0.710 0.792 0.749 Cellular Phone English 0.718 0.761 0.739 MP3 Player English 0.692 0.818 0.750 DVD Player English 0.743 0.797 0.770 文献[4]Popescu等2005 PMI Assessment 语料 Digital Camera 1 English 0.89 0.80 0.84 Digital Camera 2 English 0.87 0.74 0.80 Cellular Phone English 0.89 0.74 0.81 MP3 Player English 0.86 0.80 0.83 DVD Player English 0.90 0.78 0.84 文献[8]Xu等2012 Skip-Bigram +关联规则+剪枝 语料 Mobile Phone Chinese 0.4081 0.9529 0.5715 Digital Camera Chinese 0.3828 0.7153 0.4987 文献[9]Li等2015 文献[3]的基础上+基于词序的过滤+基于PMI-IR的过滤 语料 Mobile Phone 1 Chinese 0.732 0.667 0.698 Mobile Phone 2 Chinese 0.791 0.850 0.819 Digital Camera 1 Chinese 0.721 0.756 0.738 Digital Camera 2 Chinese 0.719 0.639 0.676 1实验结果分别表示精确率(Precision)、召回率(Recall)和F1值. 表 2 基于模板规则的抽取方法比较
Table 2 Comparison of pattern-based extraction methods
文献 方法 级别 数据集 语言 实验结果1 文献[10]Zhuang等2006 Dependency template, Supervised 语料 IMDb Movie Reviews English 0.483 0.585 0.5292 文献[19]刘鸿宇等2010 句法路径+词频过滤+ PMI过滤+名词剪枝 句子 Car Chinese 0.3126 0.4127 0.3557 (S) 0.4513 0.5958 0.5136 (L) Camera Chinese 0.3219 0.4006 0.3569 (S) 0.4556 0.567 0.5052 (L) Phone Chinese 0.3472 0.381 0.3633 (S) 0.4976 0.546 0.5206 (L) NoteBook Chinese 0.3379 0.4566 0.3883 (S) 0.4693 0.6342 0.5394 (L) 文献[13]Qiu等2011 Double propagation 语料 D1 English 0.87 0.81 0.84 D2 English 0.90 0.81 0.85 D3 English 0.90 0.86 0.88 D4 English 0.81 0.84 0.82 D5 English 0.92 0.86 0.89 1实验结果中S表示Strict评测方式, L表示Lenient评测方式.
2Based on feature-opinion pairs.表 3 基于图论的抽取方法比较
Table 3 Comparison of graph-based extraction methods
文献 方法 级别 数据集 语言 实验结果 文献[18]Liu等2012 词对齐+随机游走 语料 Camera Chinese 0.75 0.81 0.78 Car Chinese 0.71 0.71 0.71 Laptop Chinese 0.61 0.85 0.71 Phone Chinese 0.83 0.74 0.78 Hotel English 0.71 0.80 0.75 MP3 English 0.70 0.82 0.76 Restaurant Chinese 0.80 0.84 0.82 D1 English 0.84 0.85 0.84 D2 English 0.87 0.85 0.86 D3 English 0.88 0.89 0.88 D4 English 0.81 0.85 0.83 D5 English 0.89 0.87 0.88 文献[20]Xu等2013 依存句法分析+随机游走+直推式支持向量机 语料 D1 English 0.86 0.82 0.84 D2 English 0.88 0.83 0.85 D3 English 0.89 0.86 0.87 D4 English 0.83 0.86 0.84 D5 English 0.89 0.85 0.87 文献[21]Zhou等2013 标签传播 句子 Tencent Weibo Chinese 0.43 0.39 0.41 (Strict)
0.61 0.55 0.58 (Soft)表 4 IOB和IOBES标注例子
Table 4 Example of IOB and IOBES annotation
A few tips : skip the turnip cake and roast pork buns . IOB O O O O O O B I O B I I O IOBES O O O O O O B E O B I E O 表 5 基于CRF模型抽取方法比较
Table 5 Comparison of CRF-based extraction methods
文献 方法 级别 数据集 语言 实验结果 文献[25]Jakob等20101 CRF (Lexicon-related features) 句子 Movies English 0.749 0.661 0.702 Web Services English 0.722 0.526 0.609 Cars English 0.622 0.414 0.497 Cameras English 0.614 0.423 0.500 文献[27]徐冰等2011 CRF (浅层句法特征+启发式位置特征) 句子 数码相机 Chinese 0.5097 0.3579 0.4206 (S) 0.7295 0.5122 0.6019 (L) 手机 Chinese 0.5679 0.3631 0.4430 (S) 0.7761 0.4962 0.6054 (L) 笔记本 Chinese 0.5843 0.4200 0.4887 (S) 0.7692 0.5529 0.6433 (L) 汽车 Chinese 0.4302 0.2060 0.2786 (S) 0.6265 0.3001 0.4058 (L) 文献[31]Liao等2016 CRF (Lexicon-related features + Syntactic and semantic information) 句子 COAE 2014微博数据 Chinese 0.6901 0.4605 0.5523 (S) 0.7432 0.4855 0.5873 (L) 1作者还进行了跨领域的实验, 这里只给出单领域的结果. 表 6 基于深度学习的抽取方法比较
Table 6 Comparison of deep learning based extraction methods
文献 方法 级别 数据集 语言 实验结果 文献[30]Liu等2015 Recurrent Neural Networks + Word Embedding + Linguistic Features 句子 Laptop1 English 0.7457 (F1)3 0.7500 (F1)4 Restaurant1 English 0.8206 (F1)3 0.8082 (F1)4 文献[28]Wang等2016 Dependency-Tree Recursive Neural Networks + CRF + Linguistic/Lexicon Features (Name List and POS Tag) 句子 Laptop1 English 0.7809 (F1) Restaurant1 English 0.8473 (F1) 文献[29]Yin等2016 Word Embedding + Dependency Path Embedding + CRF 句子 Laptop1 English 0.7516 (F1) Restaurant1 English 0.8497 (F1) Restaurant2 English 0.6973 (F1) 文献[32]Poria等2016 Convolutional Neural Network + Linguistic Patterns 句子 Laptop1 English 0.8672 0.7835 0.8232 Restaurant1 English 0.8827 0.8610 0.8717 1SemEval-2014 Task 4数据集
2SemEval-2015 Task 12数据集
3双向Elman Type RNN + Amazon词向量+语言学特征
4LSTM-RNN + Amazon词向量+语言学特征表 7 在Customer Review Datasets上的实验结果
Table 7 Experimental results on Customer Review Datasets
文献 方法 实验结果 准确率(%) 召回率(%) F1值 文献[3], 2004 Frequency-based 72.20 79.80 75.81 文献[4], 2005 PMI 88.20 77.20 82.33 文献[13], 2011 Double Propagation 88.00 83.60 85.74 文献[18], 2012 Word Alignment + Random Walk 85.80 86.20 86.00 文献[35], 2014 Rule-based 89.41 91.42 90.40 文献[32], 2016 CNN-based 90.19 86.18 88.14 表 8 在SemEval-2014 Task 4 ABSA Datasets上的实验结果
Table 8 Experimental results on SemEval-2014 Task 4 ABSA Datasets
文献 方法 实验结果1 准确率(%) 召回率(%) F1值 文献[36], 2014 Frequency-based 23.00 25.00 24.00 37.00 40.00 38.00 文献[37], 2014 Pattern-based 32.10 42.50 36.60 57.50 64.50 60.80 文献[38], 2014 CRF-based N/A N/A 74.55 N/A N/A 79.62 文献[32], 2016 Convolutional Neural Network + Linguistic Patterns 86.72 78.35 82.32 88.27 86.10 87.17 1上行表示Laptop领域数据集实验结果, 下行表示Restaurant领域数据集实验结果. 表 9 各种方法优缺点比较
Table 9 Comparison of advantages and disadvantages of various methods
方法 优点 缺点 基于频率的方法 方法简单直观, 在产品评论领域可以取得较好效果 抽取非频繁评价对象需要额外手段 相似领域间迁移容易 难以捕捉句子含义 不相似领域间迁移效果差, 如新闻评论领域 基于模板规则的方法 时间复杂度低 依赖依存句法分析器的质量 不需要大量标注语料 编制模板规则需要专家知识 基于图论的方法 结合了评价对象和情感词的共现频率关系 没考虑无形容词性评价词的句子 领域可移植性强 频繁噪音词和非频繁长尾词需要进一步筛选 基于CRF的方法 识别准确率高 需要大量训练语料 可以任意添加特征 模型训练时间长 领域迁移则需要重新训练 基于深度学习的方法 避免大量特征工程工作 领域相关词向量训练耗时 识别效果好 需要大量标注训练语料 从一定程度上能从语义角度分析评价对象 模型训练时间复杂度高 领域迁移困难 -
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