fintech-algorithms
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Log Loss

Install and import#

bash
npm install fintech-algorithms
ts
import { logLoss } from "fintech-algorithms/model-validation-and-backtesting/classification-and-score-validation/log-loss";

Signature#

logLoss(inputs)

Worked example#

verified This is the worked example published in the article, replayed by the test suite on every run. The output cannot drift.

Input#

inputs
{
  "records": [
    {
      "id": "R01",
      "label": 1,
      "score": 0.95,
      "probability": 0.92,
      "weight": 1,
      "sector": "Banking",
      "country": "Egypt",
      "regime": "Expansion",
      "score_available_at": "2025-01-01T00:00:00Z",
      "label_available_at": "2026-01-01T00:00:00Z"
    },
    {
      "id": "R02",
      "label": 0,
      "score": 0.9,
      "probability": 0.88,
      "weight": 1,
      "sector": "Insurance",
      "country": "Egypt",
      "regime": "Expansion",
      "score_available_at": "2025-01-01T00:00:00Z",
      "label_available_at": "2026-01-01T00:00:00Z"
    },
    {
      "id": "R03",
      "label": 1,
      "score": 0.9,
      "probability": 0.84,
      "weight": 1,
      "sector": "Markets",
      "country": "Saudi Arabia",
      "regime": "Expansion",
      "score_available_at": "2025-01-01T00:00:00Z",
      "label_available_at": "2026-01-01T00:00:00Z"
    }
  ],
  "evaluation_cutoff": "2026-06-30T00:00:00Z",
  "epsilon": 1e-15
}

Call#

logLoss(inputs)

Returns#

object with 6 fields: log_loss, clipped_count, epsilon, weight_sum, event_rate, state

{
  "log_loss": 0.7086022750977335,
  "clipped_count": 0,
  "epsilon": 1e-15,
  "weight_sum": 24,
  "event_rate": 0.4166666666666667,
  "state": "probability-evaluated"
}

Other exports#

This module also exports rocCurveAndRocAuc, precisionRecallCurveAndPrAuc, brierScore, reliabilityDiagramAndExpectedCalibrationError, gainsLiftAndDecileCapture, costSensitiveThresholdOptimization, scoreStabilityAndMigrationMatrix, sliceBasedValidationBySectorCountryAndRegime, rareEventBacktestAndConfidenceBounds, calculate. Every module additionally exports run as an alias of its primary function, and a meta object carrying its catalog id, domain, family, shape and article URL.

Diagrams#

Log Loss — article hero
Log Loss — decision boundaries
Log Loss — method selection
Log Loss — system map

How it works#

This page states the contract — how to call it correctly. The article explains the concept: why it works, and where it breaks.

Read the article →

References#

The rest of the Classification and Score Validation family#