/
followers_count.go
97 lines (78 loc) · 1.99 KB
/
followers_count.go
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// Copyright 2014-2015 The DevMine authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
package features
import (
"database/sql"
"errors"
"github.com/DevMine/featscomp/util"
)
type followersCount struct {
name string
db *sql.DB
}
var _ Feature = (*followersCount)(nil)
// NewFollowersCount creates a new followers count feature.
func NewFollowersCount(name string, db *sql.DB) (*followersCount, error) {
if name == "" {
return nil, errors.New("nbFollwers: name cannot be empty")
}
if db == nil {
return nil, errors.New("followersCount: db cannot be nil")
}
return &followersCount{name: name, db: db}, nil
}
// Score computes the scores of the followers count feature.
func (n followersCount) Score() error {
if err := deleteOldScores(n.db, n.name); err != nil {
return err
}
rows, err := n.db.Query(
`SELECT u.id, ghu.followers_count
FROM users AS u
LEFT JOIN gh_users AS ghu ON u.id=ghu.user_id`)
if err != nil {
return err
}
defer rows.Close()
featID, err := util.FindFeatureID(n.db, n.name)
if err != nil {
return err
}
var followers []float64
var userIDs []int64
var maxVal float64
for rows.Next() {
var userID int64
var followersCount *int64
if err := rows.Scan(&userID, &followersCount); err != nil {
return err
}
var followersCountF float64
if followersCount != nil {
followersCountF = float64(*followersCount)
}
if followersCountF > maxVal {
maxVal = followersCountF
}
followers = append(followers, followersCountF)
userIDs = append(userIDs, userID)
}
if err := rows.Err(); err != nil {
return err
}
coeff := 1.0 / maxVal
for i, f := range followers {
if _, err = n.db.Exec(
`INSERT INTO scores(user_id, feature_id, score)
VALUES($1, $2, $3)`,
userIDs[i], featID, f*coeff); err != nil {
return err
}
}
return nil
}
// Name returns the name of the feature.
func (n followersCount) Name() string {
return n.name
}