CN108460012A - A kind of name entity recognition method based on GRU-CRF - Google Patents

A kind of name entity recognition method based on GRU-CRF Download PDF

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Publication number
CN108460012A
CN108460012A CN201810102699.0A CN201810102699A CN108460012A CN 108460012 A CN108460012 A CN 108460012A CN 201810102699 A CN201810102699 A CN 201810102699A CN 108460012 A CN108460012 A CN 108460012A
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gru
crf
entity recognition
name entity
word
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Inventor
谢金宝
李佰蔚
殷楠楠
谢桂英
王玉静
王滨生
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Harbin University of Science and Technology
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Harbin University of Science and Technology
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    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F40/00Handling natural language data
    • G06F40/20Natural language analysis
    • G06F40/279Recognition of textual entities
    • G06F40/289Phrasal analysis, e.g. finite state techniques or chunking
    • G06F40/295Named entity recognition
    • GPHYSICS
    • G06COMPUTING; CALCULATING OR COUNTING
    • G06FELECTRIC DIGITAL DATA PROCESSING
    • G06F40/00Handling natural language data
    • G06F40/20Natural language analysis
    • G06F40/279Recognition of textual entities
    • G06F40/289Phrasal analysis, e.g. finite state techniques or chunking

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  • Engineering & Computer Science (AREA)
  • Theoretical Computer Science (AREA)
  • Health & Medical Sciences (AREA)
  • Artificial Intelligence (AREA)
  • Audiology, Speech & Language Pathology (AREA)
  • Computational Linguistics (AREA)
  • General Health & Medical Sciences (AREA)
  • Physics & Mathematics (AREA)
  • General Engineering & Computer Science (AREA)
  • General Physics & Mathematics (AREA)
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Abstract

The invention discloses a kind of name entity recognition methods based on GRU CRF, belong to natural language processing field.In order to further increase the recognition effect of name Entity recognition, GRU networks are combined by the present invention with CRF, and sentence characteristics are extracted using GRU networks, carry out last entity mark in conjunction with CRF to complete name Entity recognition.The features such as GRU has parameter few, and training speed is fast, reduces the time used when being trained to large-scale data, and CRF pairs of position can use the information marked during being labeled, and there is good entity to mark effect.GRU network applications in name Entity recognition fields, the parameter of network internal are reduced on the basis of reaching mark effect, improves training effectiveness, has good application prospect, can be widely applied to the Entity recognition occasion in each field by the present invention.

Description

A kind of name entity recognition method based on GRU-CRF
Technical field
The present invention relates to natural language processing more particularly to a kind of name entity recognition methods based on GRU-CRF.
Background technology
With the fast development of Internet technology, the mankind have been accustomed to obtaining a large amount of knowledge from network, and therefore, name is real The research of body recognition methods has obtained extensive concern as people are improved from method network acquisition and find new knowledge.Life Name Entity recognition is a basic task in natural language processing field, and is the research in natural language processing field Hot spot, the method learnt from the method based on early dictionary and rule to conventional machines, then in recent years based on deep learning Method, recognition effect are constantly improving.Condition random field (Conditional Random Field, CRF) is natural in recent years Language Processing field is usually used in naming the algorithm of Entity recognition, selects some characteristic functions with Manual definition as feature Template is named Entity recognition research, can be into for the given position in sentence, between different feature templates Row combines to form a new feature templates.Sentence mark is carried out using feature templates, but CRF is for naming Entity recognition With limitation, overall effect is less desirable.Recognition with Recurrent Neural Network (Recurrent Neural Networks, RNN) is Through achieving extensive use in numerous natural language processings, but RNN is easy to that gradient disappearance problem occurs in training, this Gradient cannot always hand in longer sequence when causing to train, and make RNN that can not capture the influence of long range.Length Phase memory network (Long Short-TermMemory, LSTM) solves the influence of long range information loss, has good Therefore effect, but since LSTM structures are relative complex, result in the need for a large amount of learning time is badly in need of a kind of can both solving at present Certainly gradient disappearance problem, and have the neural network model of shorter learning time, it is carried by scholars such as Kyunghyun Cho within 2014 Thresholding Recursive Networks Recognition with Recurrent Neural Network (Gated Recurrent Unit, GRU) is gone out, it forgets door and input by LSTM's The advantages of door has synthesized a single update door, had not only remained LSTM algorithms, but also the algorithm of LSTM can be simplified, subtract significantly The e-learning time is lacked, but there is no GRU is combined the related patents named applied to entity with CRF at present.
Invention content
The problem of for above name entity recognition method, the present invention utilize GRU neural networks and condition random Field CRF is combined, and proposes a kind of name entity recognition method based on GRU-CRF.
A kind of name entity recognition method based on GRU-CRF, includes the following steps:
Step (1):Language material is divided into training set and test set;
Step (2):Training set is pre-processed;
Step (3):Each word in training set and test set sentence is indicated with one-hot vectors;
Step (4):The word vector generated by training set is input in GRU networks and carries out feature extraction;
Step (5):Sequence labelling is carried out in conjunction with CRF;
Step (6):Model training;
Step (7):Model measurement.
It is described that language material is carried out in preprocessing process, first training set is segmented using participle software, then to participle Each word afterwards carries out BIO labels, is finally trained to word2vec using the training set after label.
It is as follows that the GRU networks carry out contained calculating in feature extraction:
The update door formula of GRU is:
zt=σ (Uzxt+Wzst-1)
Wherein, ztFor the feature vector of the update door output of GRU, σ is sigmoid functions, UzAnd WzFor training parameter, xt For the word vector of t moment, st-1For xt-1The feature vector of corresponding GRU outputs, stFor xtThe feature of corresponding GRU output to Amount,
The resetting door formula of GRU is:
rt=σ (Urxt+Wrst-1)
Wherein, rtFor the feature vector of the resetting door output of GRU, UrAnd WrFor training parameter,
Hidden state equation is:
ht=tanh (Uhxt+Wh(st-1*rt))
Wherein, htFor the hidden state vector of t moment, UhAnd WhFor training parameter,
xtThe corresponding output vector of word vector is:
st=(1-zt)*ht+zt*st-1
GRU extracts the matrix M=(S of sentence characteristics1, S2, Sn), wherein n is the number of word contained by sentence.
The sequence labelling computational methods of the CRF are:
With x=(x1, x2, xn) it is expressed as the sentence that word number is n;With y=(y1, y2, yn) indicate sentence Word number contained by son is the annotated sequence of n, defines the sequence and is scored at:
Wherein, M is the eigenvectors matrix obtained by GRU networks, and A is the transfer matrix of CRF, to score (x, y) into Row index and standardization obtain the probability value p (x | y) of annotated sequence:
Wherein y'=(y1', y2', yn'), for the sequence that may be marked.
When the model training, using maximal condition Likelihood estimation, selection makes the maximum parameter of log-likelihood, It is as follows for the log-likelihood of training sample (x, y):
During the model measurement, solved using the Viterbi algorithm of Dynamic Programming:
WhereinFor optimal path, the annotated sequence of as CRF outputs.
Advantageous effect:
1, the present invention need not carry out word segmentation processing in the practical stage to text, i.e., other participles need not be used soft Part solves dependence of the prior art to participle software, also improves the independence of text-processing.
2, the present invention reduces network with GRU neural networks on the basis of remaining LSTM neural network advantages Learning time improves e-learning efficiency.
3, the method that the present invention is combined using GRU with CRF, takes full advantage of deep learning and counts excellent with Probability Gesture.
4, the present invention uses the Viterbi algorithm of Dynamic Programming, and compared to the method for exhaustion, algorithm is more simple and effective.
Description of the drawings
Fig. 1 is that GRU-CRF models name Entity recognition overall flow figure;
Fig. 2 GRU neural network structure schematic diagrames;
Fig. 3 embodiments name Entity recognition overall flow figure.
Specific implementation mode
The exemplary embodiment of the present invention is described hereinafter in connection with attached drawing.It is understood that this place The specific embodiment of description is used only for explaining the embodiment of the present invention, rather than the restriction to the embodiment of the present invention.It further needs exist for Illustrate, illustrate only for ease of description, in attached drawing with the relevant part of the embodiment of the present invention rather than entire infrastructure, and The certain components of attached drawing have omission, zoom in or out, and do not represent the size of actual product.
The name Entity recognition overall flow figure of the present embodiment is as shown in Figure 1, with 98 years《People's Daily》Part news material Material is language material, and language material is divided into training set and test set, is pre-processed to training set, in preprocessing process, is first used Jieba segments training set, reuses word2vec softwares and is trained to the training set segmented, finally will be each Word is divided into a line and is labeled, and represents name lead-in using BIO mark collection, i.e. B-PER in annotation process, I-PER represents name Non- lead-in, B-LOC represent place name lead-in, and I-LOC represents the non-lead-in of place name, and B-ORG represents institution term lead-in, I-ORG generations The non-lead-in of mechanism of table organization, O represent the part that the word is not belonging to name entity.By each sentence of the training set after mark Son indicates that the word2vec that utilization has been trained is by each word vectorization of training set with one-hot forms, further, utilizes Word2vec after training is vectorial for the dense word of low-dimensional by one-hot DUAL PROBLEMS OF VECTOR MAPPINGs by each word in sentence, selects here 100 dimensions, naturally it is also possible to select 300 dimensions.Using the word vector matrix of generation as the input of GRU neural networks, the main knot of GRU Structure is as shown in Fig. 2, ztFor the output feature vector of the update door of GRU, σ is sigmoid functions, xtFor the word vector of t moment, st For xtThe feature vector of corresponding GRU outputs, st-1For xt-1The feature vector of corresponding GRU outputs, rtIt is defeated for the resetting door of GRU The feature vector gone out, htFor the hidden state vector of t moment, xtThe corresponding output vector of word vector is:st=(1-zt)*h+zt* st-1, wherein * expressions are multiplied by element, i.e., the new vector that element multiplication obtains one by one between vector, finally by GRU nets Network extracts the matrix M=(S of sentence characteristics1, S2, Sn), n is the number of word contained by sentence.Be input to GRU networks it Before, dropout layers of setting can be first passed through to alleviate over-fitting, then extract sentence characteristics using GRU networks.Embodiment Experimental situation is based under python running environment, and major parameter is set as dropout=0.5, and batch_size takes 64, learns Habit rate is 0.001, and iterations are 100 wheels, by the GRU eigenvectors matrix M extracted and are used as CRF layers of condition random field Input, the representation method of the CRF uses matrix-style, with x=(x1, x2, xn) word number is expressed as n's Sentence;With y=(y1, y2, yn) indicate the annotated sequence that word number contained by sentence is n, it defines the sequence and is scored at:
Wherein, M is the eigenvectors matrix M obtained by GRU networks, and A is the transfer matrix of CRF, to score (x, y) Indexation and standardization are carried out, the probability value p (x | y) of annotated sequence is obtained:
Wherein y'=(y1', y2', yn'), for the sequence that may be marked;
When model training, when solving probability value, asked using the method for maximal possibility estimation, and using log-likelihood Solution.Using annotated sequence y and the probability value p (x | y) of annotated sequence y is obtained, model is trained.
Annotation process when model measurement as shown in figure 3, test set is indicated with one-hot, what utilization had been trained Word vector matrix after vectorization is input in model by word2vec by each word vectorization of test set, CRF layers into The sequence labelling of row Sentence-level during model measurement, is solved, utilization is each using the Viterbi algorithm of Dynamic Programming The suboptimization of step achievees the effect that global optimization, last output are:
WhereinFor optimal path, the annotated sequence of as CRF outputs, last mark knot Fruit is as follows:
PER:Name, LOC:Place name, ORG:Institution term
Finally illustrate, although describing the present invention according to the embodiment of limited quantity, benefit from above description, It will be understood by those skilled in the art that in the scope of the present invention thus described, it can be envisaged that other implementations Example.Additionally, it should be noted that the language used in this specification primarily to readable and introduction purpose and select, and It is not configured to explain or limits subject of the present invention and select.Therefore, without departing from the scope of the appended claims and In the case of objective, for those skilled in the art, many modifications and changes are obvious.It is right In the scope of the present invention, the disclosure done to the present invention is illustrative and not restrictive, and the scope of the present invention is by appended Claims limited.

Claims (6)

1. a kind of name entity recognition method based on GRU-CRF, which is characterized in that include the following steps:
Step (1):Language material is divided into training set and test set;
Step (2):Training set is pre-processed;
Step (3):Each word in training set and test set sentence is indicated with one-hot vectors;
Step (4):The word vector generated by training set is input in GRU networks and carries out feature extraction;
Step (5):Sequence labelling is carried out in conjunction with CRF;
Step (6):Model training;
Step (7):Model measurement.
2. a kind of name entity recognition method based on GRU-CRF according to claim 1, which is characterized in that described right Language material carry out preprocessing process in, first using participle software training set is segmented, then to each word after participle into Row BIO labels, are finally trained word2vec using the training set after label.
3. a kind of name entity recognition method based on GRU-CRF according to claim 1, which is characterized in that the GRU It is as follows that network carries out contained calculating in feature extraction:
The update door formula of GRU is:
zt=σ (Uzxt+Wzst-1)
Wherein, ztFor the feature vector of the update door output of GRU, σ is sigmoid functions, UzAnd WzFor training parameter, xtFor t when The word vector at quarter, st-1For xt-1The feature vector of corresponding GRU outputs, stFor xtThe feature vector of corresponding GRU outputs,
The resetting door formula of GRU is:
rt=σ (Urxt+Wrst-1)
Wherein, rtFor the feature vector of the resetting door output of GRU, UrAnd WrFor training parameter,
Hidden state equation is:
ht=tanh (Uhxt+Wh(st-1*rt))
Wherein, htFor the hidden state vector of t moment, UhAnd WhFor training parameter,
xtThe corresponding output vector of word vector is:
st=(1-zt)*ht+zt*st-1
GRU extracts the matrix M=(S of sentence characteristics1, S2, Sn), wherein n is the number of word contained by sentence.
4. a kind of name entity recognition method based on GRU-CRF according to claim 1, which is characterized in that the CRF Sequence labelling computational methods be:
With x=(x1, x2, xn) it is expressed as the sentence that word number is n;With y=(y1, y2, yn) indicate sentence institute Number containing word is the annotated sequence of n, defines the sequence and is scored at:
Wherein, M is the eigenvectors matrix obtained by GRU networks, and A is the transfer matrix of CRF, is referred to score (x, y) Numberization and standardization obtain the probability value p (x | y) of annotated sequence:
Wherein y'=(y1', y2', yn'), for the sequence that may be marked.
5. a kind of name entity recognition method based on GRU-CRF according to claim 1 or 4, which is characterized in that described When model training, using maximal condition Likelihood estimation, selection makes the maximum parameter of log-likelihood, for training sample The log-likelihood of (x, y) is as follows:
6. a kind of name entity recognition method based on GRU-CRF according to claim 1 or 4, which is characterized in that in institute During stating model measurement, solved using the Viterbi algorithm of Dynamic Programming:
WhereinFor optimal path, the annotated sequence of as CRF outputs.
CN201810102699.0A 2018-02-01 2018-02-01 A kind of name entity recognition method based on GRU-CRF Pending CN108460012A (en)

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Cited By (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109284361A (en) * 2018-09-29 2019-01-29 深圳追科技有限公司 A kind of entity abstracting method and system based on deep learning
CN109299457A (en) * 2018-09-06 2019-02-01 北京奇艺世纪科技有限公司 A kind of opining mining method, device and equipment
CN109741732A (en) * 2018-08-30 2019-05-10 京东方科技集团股份有限公司 Name entity recognition method, name entity recognition device, equipment and medium
CN109871535A (en) * 2019-01-16 2019-06-11 四川大学 A kind of French name entity recognition method based on deep neural network
CN110222343A (en) * 2019-06-13 2019-09-10 电子科技大学 A kind of Chinese medicine plant resource name entity recognition method
CN110298043A (en) * 2019-07-03 2019-10-01 吉林大学 A kind of vehicle name entity recognition method and system
CN110717331A (en) * 2019-10-21 2020-01-21 北京爱医博通信息技术有限公司 Neural network-based Chinese named entity recognition method, device, equipment and storage medium
WO2020133039A1 (en) * 2018-12-27 2020-07-02 深圳市优必选科技有限公司 Entity identification method and apparatus in dialogue corpus, and computer device
CN111382569A (en) * 2018-12-27 2020-07-07 深圳市优必选科技有限公司 Method and device for recognizing entities in dialogue corpus and computer equipment
CN112256828A (en) * 2020-10-20 2021-01-22 平安科技(深圳)有限公司 Medical entity relationship extraction method and device, computer equipment and readable storage medium

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106776711A (en) * 2016-11-14 2017-05-31 浙江大学 A kind of Chinese medical knowledge mapping construction method based on deep learning
CN106980608A (en) * 2017-03-16 2017-07-25 四川大学 A kind of Chinese electronic health record participle and name entity recognition method and system
WO2017130434A1 (en) * 2016-01-28 2017-08-03 楽天株式会社 Computer system, method, and program for transferring named entity recognition model for multiple languages
CN107644014A (en) * 2017-09-25 2018-01-30 南京安链数据科技有限公司 A kind of name entity recognition method based on two-way LSTM and CRF

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2017130434A1 (en) * 2016-01-28 2017-08-03 楽天株式会社 Computer system, method, and program for transferring named entity recognition model for multiple languages
CN106776711A (en) * 2016-11-14 2017-05-31 浙江大学 A kind of Chinese medical knowledge mapping construction method based on deep learning
CN106980608A (en) * 2017-03-16 2017-07-25 四川大学 A kind of Chinese electronic health record participle and name entity recognition method and system
CN107644014A (en) * 2017-09-25 2018-01-30 南京安链数据科技有限公司 A kind of name entity recognition method based on two-way LSTM and CRF

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
MOURAD GRIDACH 等: "Arabic Named Entity Recognition : A Bidirectional GRU-CRF Approach", 《HTTPS://WWW.RESEARCHGATE.NET/PUBLICATION/328165330》 *
李佰蔚: "基于GRU-CRF的中文命名实体识别方法研究", 《中国优秀硕士学位论文全文数据库 信息科技辑》 *

Cited By (16)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN109741732A (en) * 2018-08-30 2019-05-10 京东方科技集团股份有限公司 Name entity recognition method, name entity recognition device, equipment and medium
CN109741732B (en) * 2018-08-30 2022-06-21 京东方科技集团股份有限公司 Named entity recognition method, named entity recognition device, equipment and medium
CN109299457A (en) * 2018-09-06 2019-02-01 北京奇艺世纪科技有限公司 A kind of opining mining method, device and equipment
CN109284361A (en) * 2018-09-29 2019-01-29 深圳追科技有限公司 A kind of entity abstracting method and system based on deep learning
CN111382569A (en) * 2018-12-27 2020-07-07 深圳市优必选科技有限公司 Method and device for recognizing entities in dialogue corpus and computer equipment
CN111382569B (en) * 2018-12-27 2024-05-03 深圳市优必选科技有限公司 Method and device for identifying entity in dialogue corpus and computer equipment
WO2020133039A1 (en) * 2018-12-27 2020-07-02 深圳市优必选科技有限公司 Entity identification method and apparatus in dialogue corpus, and computer device
CN109871535A (en) * 2019-01-16 2019-06-11 四川大学 A kind of French name entity recognition method based on deep neural network
CN109871535B (en) * 2019-01-16 2020-01-10 四川大学 French named entity recognition method based on deep neural network
CN110222343A (en) * 2019-06-13 2019-09-10 电子科技大学 A kind of Chinese medicine plant resource name entity recognition method
CN110298043B (en) * 2019-07-03 2023-04-07 吉林大学 Vehicle named entity identification method and system
CN110298043A (en) * 2019-07-03 2019-10-01 吉林大学 A kind of vehicle name entity recognition method and system
CN110717331A (en) * 2019-10-21 2020-01-21 北京爱医博通信息技术有限公司 Neural network-based Chinese named entity recognition method, device, equipment and storage medium
CN110717331B (en) * 2019-10-21 2023-10-24 北京爱医博通信息技术有限公司 Chinese named entity recognition method, device and equipment based on neural network and storage medium
CN112256828A (en) * 2020-10-20 2021-01-22 平安科技(深圳)有限公司 Medical entity relationship extraction method and device, computer equipment and readable storage medium
CN112256828B (en) * 2020-10-20 2023-08-08 平安科技(深圳)有限公司 Medical entity relation extraction method, device, computer equipment and readable storage medium

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Application publication date: 20180828