问题
In the template for training CRF++, how can I include a custom dictionary.txt file for listed companies, another for popular European foods, for eg, or just about any category.
Then provide a sample training data for each category whereby it learns how those specific named entites are used within a context for that category.
In this way, I as well as the system, can be sure it correctly understood how certain named entites are structured in a text, whether a tweet or a Pulitzer prize winning news article, instead of providing hundred megabytes of data.
This would be rather cool. Model would have a definite dictionary of known entites (which does not need to be expanded) and a statistical approach on how those known entites are structured in human text.
PS - Just for clarity, not yearning for a regex ner. These are only cool if you got lots in the dictionary, lots of rule and lots of dulltime.
回答1:
I think what you are talking about is Gazetteers list (dictionary.txt).
You would have to include corresponding feature for a word in training data and then specify it in template file.
For Example: Your list contains the entity: Hershey's
and training data has a sentence: I like Hershey's chocolates.
So when you arrange the data in CoNLL Format (for CRF++), you can add a column (which shall have values 0 or 1 , indicating is the word is present in dictionary) which will have 0 value for all words, except Hershey's. You also have to include this column as feature in template file.
To get a better understanding on Template File and NER training with CRF++, you can watch the below videos and comment your doubts :)
1) https://youtu.be/GJHeTvDkIaE
2) https://youtu.be/Ur5umC4BwN4
EDIT: (after viewing the OP's comment)
Sample Training Data with extra features: https://pastebin.com/fBgu8c67
I've added 3 features. The IsCountry feature value ( 1 or 0 ) can be obtained from a Gazetteers list of countries. The other 2 features can be computed offline. Note that Headers are added in file for reference only, should not be include in training data file.
Sample Template File for the above data : https://pastebin.com/LPvAGCVL
Note that, Test Data should also be in the same format as Train Data, with the same features / same no of columns.
来源：https://stackoverflow.com/questions/43560764/learnig-ner-using-category-list