Adding Text Processing to Classification Machine Learning in Oracle Machine Learning

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One of the typical machine learning functions is Classification. This is in widespread use across most domains and geographic regions. I’ve written several blog posts on this topic over many years (and going back many, many year) on how to do this using Oracle Machine Learning (OML) (formally known as Oracle Advanced Analytic and in the Oracle Data Miner tool in SQL Developer). Just do a quick search of my blog to find some of these posts.

When it comes to Classification problems, typically the data set will be contain your typical categorical and numerical variables/features. The Automatic Data Preparation (ADP) feature of OML where it automatically pre-processes and transforms these variable for input to the machine learning algorithm. This greatly reduces the boring work of the data scientist and increases their productivity.

But sometimes data sets come with text descriptions. These will contain production descriptions, free format text, and other descriptive data, for example product reviews. But how can this information be included as part of the input data set to the machine learning algorithms. Oracle allows this kind of input data, and a letting bit of setup is needed to tell Oracle how to process the data set. This uses the in-database feature of Oracle Text.

The following example walks through an example of the steps needed to pre-process and include the text processing as part of the machine learning algorithm.

The data set: The data used to illustrate this and to show the steps needed, is a data set from Kaggle webiste. This data set contains 130K Wine Reviews. This data set contain descriptive information of the wine with attributes about each wine including country, region, number of points, price, etc as well as a text description contain a review of the wine.

The following are 2 files containing the DDL (to create the table) and then Import the data set (using sql script with insert statements). These can be run in your schema (in order listed below).

  1. Create table WINEREVIEWS_130K_IMP
  2. Insert records into WINEREVIEWS_130K_IMP table

I’ll leave the Data Exploration to you to do and to discover some early insights.

The ML Question

I want to be able to predict if a wine is a good quality wine, based on the prices and different characteristics of the wine?

Data Preparation

To be able to answer this question the first thing needed is to define a target variable to identify good and bad wines. To do this create a new attribute/feature called POINTS_BIN and populate it based on the number of points a wine has. If it has >90 points it is a good wine, if <90 points it is a bad wine.

ALTER TABLE WineReviews130K_bin ADD POINTS_BIN VARCHAR2(15);

UPDATE WineReviews130K_bin
SET POINTS_BIN = 'GT_90_Points'
WHERE winereviews130k_bin.POINTS >= 90;

UPDATE WineReviews130K_bin
SET POINTS_BIN = 'LT_90_Points'
WHERE winereviews130k_bin.POINTS < 90;

alter table WineReviews130K_bin DROP COLUMN POINTS;

The DESCRIPTION column data type needs to be changed to CLOB. This is to allow the Text Mining feature to work correctly.

-- add a new column of data type CLOB
ALTER TABLE WineReviews130K_bin ADD (DESCRIPTION_NEW CLOB);

-- update new column with data from the DESCRIPTION attribute
UPDATE WineReviews130K_bin SET DESCRIPTION_NEW = DESCRIPTION;

-- drop the DESCRIPTION attribute from table
ALTER TABLE WineReviews130K_bin DROP COLUMN DESCRIPTION;

-- rename the new attribute to replace DESCRIPTION
ALTER TABLE WineReviews130K_bin RENAME COLUMN DESCRIPTION_NEW TO DESCRIPTION;

Text Mining Configuration

There are a number of things we need to define for the Text Mining to work, these include a Lexer, Stop Word list and preferences.

First define the Lexer to use. In this case we will use a basic one and basic settings

BEGIN 
   ctx_ddl.create_preference('mylex', 'BASIC_LEXER'); 
   ctx_ddl.set_attribute('mylex', 'printjoins', '_-'); 
   ctx_ddl.set_attribute ( 'mylex', 'index_themes', 'NO'); 
   ctx_ddl.set_attribute ( 'mylex', 'index_text', 'YES'); 
END;

Next we can define a Stop Word List. Oracle Text comes with a predefined set of Stop Word lists for most of the common languages. You can add to one of those list or create your own. Depending on the domain you are working in it might be easier to create your own and it is very straight forward to do. For example:

DECLARE
   v_stoplist_name varchar2(100);
BEGIN
   v_stoplist_name := 'mystop';
   ctx_ddl.create_stoplist(v_stoplist_name, 'BASIC_STOPLIST'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'nonetheless');
   ctx_ddl.add_stopword(v_stoplist_name, 'Mr'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'Mrs'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'Ms'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'a'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'all'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'almost'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'also'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'although'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'an'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'and'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'any'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'are'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'as'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'at'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'be'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'because'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'been'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'both'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'but'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'by'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'can'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'could'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'd'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'did'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'do'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'does'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'either'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'for'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'from'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'had'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'has'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'have'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'having'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'he'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'her'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'here'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'hers'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'him'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'his'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'how'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'however'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'i'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'if'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'in'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'into'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'is'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'it'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'its'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'just'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'll'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'me'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'might'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'my'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'no'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'non'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'nor'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'not'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'of'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'on'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'one'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'only'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'onto'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'or'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'our'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'ours'); 
   ctx_ddl.add_stopword(v_stoplist_name, 's'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'shall'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'she'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'should'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'since'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'so'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'some'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'still'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'such'); 
   ctx_ddl.add_stopword(v_stoplist_name, 't'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'than'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'that'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'the'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'their'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'them'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'then'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'there'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'therefore'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'these'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'they'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'this'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'those'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'though'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'through'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'thus'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'to'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'too'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'until'); 
   ctx_ddl.add_stopword(v_stoplist_name, 've'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'very'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'was'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'we'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'were'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'what'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'when'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'where'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'whether'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'which'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'while'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'who'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'whose'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'why'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'will'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'with'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'would'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'yet'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'you'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'your'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'yours'); 
   ctx_ddl.add_stopword(v_stoplist_name, 'drink');
   ctx_ddl.add_stopword(v_stoplist_name, 'flavors'); 
   ctx_ddl.add_stopword(v_stoplist_name, '2020');
   ctx_ddl.add_stopword(v_stoplist_name, 'now'); 
END;

Next define the preferences for processing the Text, for example what Stop Word list to use, if Fuzzy match is to be used and what language to use for this, number of tokens/words to process and if stemming is to be used.

BEGIN 
   ctx_ddl.create_preference('mywordlist', 'BASIC_WORDLIST');
   ctx_ddl.set_attribute('mywordlist','FUZZY_MATCH','ENGLISH'); 
   ctx_ddl.set_attribute('mywordlist','FUZZY_SCORE','1'); 
   ctx_ddl.set_attribute('mywordlist','FUZZY_NUMRESULTS','5000'); 
   ctx_ddl.set_attribute('mywordlist','SUBSTRING_INDEX','TRUE'); 
   ctx_ddl.set_attribute('mywordlist','STEMMER','ENGLISH'); 
END;

And the final step is to piece it all together by defining a new Text policy

BEGIN
   ctx_ddl.create_policy('my_policy', NULL, NULL, 'mylex', 'mystop', 'mywordlist');
END;

Define Settings for OML Model

We will create two models. An Attribute Importance model and a Classification model. The following defines the model parameters for each of these.

CREATE TABLE att_import_model_settings (setting_name varchar2(30), setting_value varchar2(30)); 
INSERT INTO att_import_model_settings (setting_name, setting_value)  
VALUES (''ALGO_NAME'', ''ALGO_AI_MDL'');
INSERT INTO att_import_model_settings (setting_name, setting_value) 
VALUES (''PREP_AUTO'', ''ON'');
INSERT INTO att_import_model_settings (setting_name, setting_value) 
VALUES (''ODMS_TEXT_POLICY_NAME'', ''my_policy'');
INSERT INTO att_import_model_settings (setting_name, setting_value) 
VALUES (''ODMS_TEXT_MAX_FEATURES'', ''3000'')';
CREATE TABLE wine_model_settings (setting_name varchar2(30), setting_value varchar2(30)); 
INSERT INTO wine_model_settings (setting_name, setting_value)  
VALUES (''ALGO_NAME'', ''ALGO_RANDOM_FOREST'');
INSERT INTO wine_model_settings (setting_name, setting_value) 
VALUES (''PREP_AUTO'', ''ON'');
INSERT INTO wine_model_settings (setting_name, setting_value) 
VALUES (''ODMS_TEXT_POLICY_NAME'', ''my_policy'');
INSERT INTO wine_model_settings (setting_name, setting_value) 
VALUES (''ODMS_TEXT_MAX_FEATURES'', ''3000'')';

Create the Training and Test data sets.

CREATE TABLE wine_train_data
AS SELECT id, country, description, designation, points_bin, price, province, region_1, region_2, taster_name, variety, title
FROM winereviews130k_bin 
SAMPLE (60) SEED (1);
CREATE TABLE wine_test_data
AS SELECT id, country, description, designation, points_bin, price, province, region_1, region_2, taster_name, variety, title
FROM winereviews130k_bin 
WHERE id NOT IN (SELECT id FROM wine_train_data);

All the set up is done, we can move onto the creating the machine learning models.

Create the OML Model (Attribute Importance & Classification)

We are going to create two models. The first is an Attribute Important model. This will look at the data set and will determine what attributes contribute most towards determining the target variable. As we are incorporting Texting Mining we will see what words/tokens from the DESCRIPTION attribute also contribute towards the target variable.

BEGIN
   DBMS_DATA_MINING.CREATE_MODEL(
      model_name          => 'GOOD_WINE_AI',
      mining_function     => DBMS_DATA_MINING.ATTRIBUTE_IMPORTANCE,
      data_table_name     => 'winereviews130k_bin',
      case_id_column_name => 'ID',
      target_column_name  => 'POINTS_BIN',
      settings_table_name => 'att_import_mode_settings');
END;

We can query the system views for Oracle ML to find out what are the important variables.

SELECT * FROM dm$vagood_wine_ai 
ORDER BY attribute_rank;

Here is the listing of the top 15 most important attributes. We can see from the first 15 rows and looking under column ATTRIBUTE_SUBNAME, the words from the DESCRIPTION attribute that seem to be important and contribute towards determining the value in the target attribute.

At this point you might determine, based on domain knowledge, some of these words should be excluded as they are generic for the domain. In this case, go back to the Stop Word List and recreate it with any additional words. This can be repeated until you are happy with the list. In this example, WINE could be excluded by including it in the Stop Word List.

Run the following to create the Classification model. It is very similar to what we ran above with minor changes to the name of the model, the data mining function and the name of the settings table.

BEGIN
   DBMS_DATA_MINING.CREATE_MODEL(
      model_name          => 'GOOD_WINE_MODEL',
      mining_function     => DBMS_DATA_MINING.CLASSIFICATION,
      data_table_name     => 'winereviews130k_bin',
      case_id_column_name => 'ID',
      target_column_name  => 'POINTS_BIN',
      settings_table_name => 'wine_model_settings');
END;

Apply OML Model

The model can be applied in similar ways to any other ML model created using OML. For example the following displays the wine details along with the predicted points bin values (good or bad) and the probability score (<=1) of the prediction.

SELECT id, price, country, designation, province, variety, points_bin, 
       PREDICTION(good_wine_mode USING *) pred_points_bin,
       PREDICTION_PROBABILITY(good_wine_mode USING *) prob_points_bin
FROM wine_test_data;