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classifier_shield.go
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/
classifier_shield.go
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// /home/krylon/go/src/github.com/blicero/ticker/classifier/classifier_shield.go
// -*- mode: go; coding: utf-8; -*-
// Created on 12. 10. 2022 by Benjamin Walkenhorst
// (c) 2022 Benjamin Walkenhorst
// Time-stamp: <2022-10-21 16:43:38 krylon>
package classifier
import (
"log"
"path/filepath"
"runtime"
"strings"
"github.com/blicero/shield"
"github.com/blicero/ticker/common"
"github.com/blicero/ticker/database"
"github.com/blicero/ticker/feed"
"github.com/blicero/ticker/logdomain"
"github.com/endeveit/guesslanguage"
)
// ClassifierShield is an implementation of a classifier that uses shield as
// its Bayes-engine, so to speak.
type ClassifierShield struct {
pool *database.Pool
log *log.Logger
shield map[string]shield.Shield
}
// NewShield creates and returns a new ClassifierShield.
func NewShield(pool *database.Pool) (*ClassifierShield, error) {
var (
err error
c = &ClassifierShield{
shield: map[string]shield.Shield{
"de": shield.New(
shield.NewGermanTokenizer(),
shield.NewLevelDBStore(filepath.Join(
common.ClassifierDir,
"de")),
),
"en": shield.New(
shield.NewEnglishTokenizer(),
shield.NewLevelDBStore(
filepath.Join(
common.ClassifierDir,
"en",
),
),
),
},
pool: pool,
}
)
if c.log, err = common.GetLogger(logdomain.Classifier); err != nil {
return nil, err
}
// for k, v := range c.shield {
// c.log.Printf("[DEBUG] Shield Classifier for %s: %s\n",
// k,
// spew.Sdump(v))
// }
return c, nil
} // func NewShield() (*ClassifierShield, error)
// Trains trains the Classifier.
func (c *ClassifierShield) Train() error {
var (
err error
items []feed.Item
db *database.Database
)
for k, v := range c.shield {
c.log.Printf("[DEBUG] Reset Shield instance for %s\n",
k)
if err = v.Reset(); err != nil {
c.log.Printf("[ERROR] Cannot reset Shield/%s: %s\n",
k,
err.Error())
return err
}
}
db = c.pool.Get()
defer c.pool.Put(db)
if items, err = db.ItemGetRated(); err != nil {
c.log.Printf("[ERROR] Cannot load rated Items: %s\n",
err.Error())
return err
}
for _, i := range items {
var (
s shield.Shield
lang, class, body string
)
lang, body = c.getLanguage(&i)
if s = c.shield[lang]; s == nil {
s = c.shield["en"]
}
if i.Rating >= 0.5 {
class = Good
} else {
class = Bad
}
if err = s.Learn(class, body); err != nil {
c.log.Printf("[ERROR] Failed to learn Item %d (%s): %s\n",
i.ID,
i.Title,
err.Error())
return err
}
}
return nil
} // func (c *ClassifierShield) Train() error
func (c *ClassifierShield) Learn(class string, item *feed.Item) error {
var (
err error
lang, body string
s shield.Shield
)
lang, body = c.getLanguage(item)
if s = c.shield[lang]; s == nil {
s = c.shield["en"]
}
if err = s.Learn(class, body); err != nil {
c.log.Printf("[ERROR] Failed to learn Item %d (%s): %s\n",
item.ID,
item.Title,
err.Error())
return err
}
return nil
} // func (c *ClassifierShield) Learn(class string, item *feed.Item) error
func (c *ClassifierShield) Unlearn(class string, item *feed.Item) error {
var (
err error
lang, body string
s shield.Shield
)
lang, body = c.getLanguage(item)
if s = c.shield[lang]; s == nil {
s = c.shield["en"]
}
if err = s.Forget(class, body); err != nil {
c.log.Printf("[ERROR] Failed to learn Item %d (%s): %s\n",
item.ID,
item.Title,
err.Error())
return err
}
return nil
} // func (c *ClassifierShield) Unlearn(class string, item *feed.Item) error
// Classify attempts to find a rating for a news item.
func (c *ClassifierShield) Classify(item *feed.Item) (string, error) {
var (
err error
rating, lang, body string
s shield.Shield
)
lang, body = c.getLanguage(item)
if s = c.shield[lang]; s == nil {
s = c.shield["en"]
}
if rating, err = s.Classify(body); err != nil {
return "", err
}
return rating, nil
} // func (c *ClassifierShield) Classify(item *feed.Item) (string, error)
func (c *ClassifierShield) getLanguage(item *feed.Item) (lng, fullText string) {
const (
defaultLang = "en"
blString = "Lauren Boebert buried in ridicule after claim about 1930s Germany"
)
var (
err error
lang, body string
)
body = item.Plaintext()
defer func() {
if x := recover(); x != nil {
if !strings.Contains(item.Title, blString) {
var buf [2048]byte
var cnt = runtime.Stack(buf[:], false)
c.log.Printf("[CRITICAL] Panic in getLanguage for Item %q: %s\n%s",
item.Title,
x,
string(buf[:cnt]))
}
lng = defaultLang
fullText = body
}
}()
if lang, err = guesslanguage.Guess(body); err != nil {
c.log.Printf("[ERROR] Cannot determine language of Item %q: %s\n",
item.Title,
err.Error())
lang = defaultLang
}
return lang, body
} // func getLanguage(title, description string) (string, string)