Regression_AutoML

Taxi Fare Prediction

Automated Machine Learning

Automated machine learning (AutoML) automates the end-to-end process of applying machine learning to real-world problems. Given a dataset, AutoML iterates over different data featurizations, machine learning algorithms, hyperparamters, etc. to select the best model.

Problem

This problem is to predict the fare of a taxi trip in New York City. At first glance, the fare may seem to depend simply on the distance traveled. However, taxi vendors in New York charge varying amounts for other factors such as additional passengers, paying with a credit card instead of cash, and so on. This prediction could help taxi providers give passengers and drivers estimates on ride fares.

ML Task - Regression

The generalized problem of regression is to predict some continuous value for given parameters, for example:

• predict a house prise based on number of rooms, location, year built, etc.
• predict a car fuel consumption based on fuel type and car parameters.
• predict a time estimate for fixing an issue based on issue attributes.

For all these examples, the parameter we want to predict can take any numeric value in a certain range. In other words, this value is represented by integer or float/ double, not by enum or boolean types.

Step 1: Load the Data

Load the datasets required to train and test:

 IDataView trainingDataView = mlContext.Data.LoadFromTextFile<TaxiTrip>(TrainDataPath, hasHeader: true);
 IDataView testDataView = mlContext.Data.LoadFromTextFile<TaxiTrip>(TestDataPath, hasHeader: true);

Step 2: Building a Machine Learning Model using AutoML

Instantiate and run an AutoML experiment. In doing so, specify how long the experiment should run in seconds (ExperimentTime), and set a progress handler that will receive notifications after AutoML trains & evaluates each new model.

// Run AutoML binary classification experiment
ExperimentResult<RegressionMetrics> experimentResult = mlContext.Auto()
    .CreateRegressionExperiment(ExperimentTime)
    .Execute(trainingDataView, LabelColumnName, progressHandler: new RegressionExperimentProgressHandler());

Step 3: Evaluate Model

Grab the best model produced by the AutoML experiment

ITransformer model = experimentResult.BestRun.Model;

and evaluate its quality on a test dataset that was not used in training (taxi-fare-test.csv).

Regression.Evaluate() calculates the difference between known fares and values predicted by the model to produce various metrics.

var predictions = trainedModel.Transform(testDataView);
var metrics = mlContext.Regression.Evaluate(predictions, scoreColumnName: "Score");

Step 4: Make Predictions

Using the trained model, use the Predict() API to predict the fare amount for specified trip:

//Sample: 
//vendor_id,rate_code,passenger_count,trip_time_in_secs,trip_distance,payment_type,fare_amount
//VTS,1,1,1140,3.75,CRD,15.5

var taxiTripSample = new TaxiTrip()
{
    VendorId = "VTS",
    RateCode = "1",
    PassengerCount = 1,
    TripTime = 1140,
    TripDistance = 3.75f,
    PaymentType = "CRD",
    FareAmount = 0 // To predict. Actual/Observed = 15.5
};

// Create prediction engine
var predEngine = mlContext.Model.CreatePredictionEngine<TaxiTrip, TaxiTripFarePrediction>(model);

// Score
var predictedResult = predEngine.Predict(taxiTripSample);

Console.WriteLine($"**********************************************************************");
Console.WriteLine($"Predicted fare: {predictedResult.FareAmount:0.####}, actual fare: 15.5");
Console.WriteLine($"**********************************************************************");

Finally, you can plot in a chart how the tested predictions are distributed and how the regression is performing with the implemented method PlotRegressionChart() as in the following screenshot: