the-algorithm/timelines/data_processing/ml_util/aggregation_framework/job/DataRecordFeatureCounter.scala

package com.twitter.timelines.data_processing.ml_util.aggregation_framework.job

import com.twitter.ml.api.DataRecord
import com.twitter.summingbird.Counter

/**
 * A summingbird Counter which is associated with a predicate which operates on
 * [[com.twitter.ml.api.DataRecord]] instances.
 *
 * For example, for a data record which represents a Tweet, one could define a predicate
 * which checks whether the Tweet contains a binary feature representing the presence of
 * an image. The counter can then be used to represent the the count of Tweets with
 * images processed.
 *
 * @param predicate a predicate which gates the counter
 * @param counter a summingbird Counter instance
 */
case class DataRecordFeatureCounter(predicate: DataRecord => Boolean, counter: Counter)

object DataRecordFeatureCounter {

  /**
   * Increments the counter if the record satisfies the predicate
   *
   * @param recordCounter a data record counter
   * @param record a data record
   */
  def apply(recordCounter: DataRecordFeatureCounter, record: DataRecord): Unit =
    if (recordCounter.predicate(record)) recordCounter.counter.incr()

  /**
   * Defines a feature counter with a predicate that is always true
   *
   * @param counter a summingbird Counter instance
   * @return a data record counter
   */
  def any(counter: Counter): DataRecordFeatureCounter =
    DataRecordFeatureCounter({ _: DataRecord => true }, counter)
}