Overview of data science using Spark on Azure HDInsight
This suite of topics shows how to use HDInsight Spark to complete common data science tasks such as data ingestion, feature engineering, modeling, and model evaluation. The data used is a sample of the 2013 NYC taxi trip and fare dataset. The models built include logistic and linear regression, random forests, and gradient boosted trees. The topics also show how to store these models in Azure blob storage (WASB) and how to score and evaluate their predictive performance. More advanced topics cover how models can be trained using cross-validation and hyper-parameter sweeping. This overview topic also references the topics that describe how to set up the Spark cluster that you need to complete the steps in the walkthroughs provided.
Spark and MLlib
Spark is an open-source parallel processing framework that supports in-memory processing to boost the performance of big-data analytic applications. The Spark processing engine is built for speed, ease of use, and sophisticated analytics. Spark's in-memory distributed computation capabilities make it a good choice for the iterative algorithms used in machine learning and graph computations. MLlib is Spark's scalable machine learning library that brings the algorithmic modeling capabilities to this distributed environment.
HDInsight Spark is the Azure hosted offering of open-source Spark. It also includes support for Jupyter PySpark notebooks on the Spark cluster that can run Spark SQL interactive queries for transforming, filtering, and visualizing data stored in Azure Blobs (WASB). PySpark is the Python API for Spark. The code snippets that provide the solutions and show the relevant plots to visualize the data here run in Jupyter notebooks installed on the Spark clusters. The modeling steps in these topics contain code that shows how to train, evaluate, save, and consume each type of model.
Setup: Spark clusters and Jupyter notebooks
Setup steps and code are provided in this walkthrough for using an HDInsight Spark 1.6. But Jupyter notebooks are provided for both HDInsight Spark 1.6 and Spark 2.0 clusters. A description of the notebooks and links to them are provided in the Readme.md for the GitHub repository containing them. Moreover, the code here and in the linked notebooks is generic and should work on any Spark cluster. If you are not using HDInsight Spark, the cluster setup and management steps may be slightly different from what is shown here. For convenience, here are the links to the Jupyter notebooks for Spark 1.6 (to be run in the pySpark kernel of the Jupyter Notebook server) and Spark 2.0 (to be run in the pySpark3 kernel of the Jupyter Notebook server):
Spark 1.6 notebooks
These notebooks are to be run in the pySpark kernel of Jupyter notebook server.
- pySpark-machine-learning-data-science-spark-data-exploration-modeling.ipynb: Provides information on how to perform data exploration, modeling, and scoring with several different algorithms.
- pySpark-machine-learning-data-science-spark-advanced-data-exploration-modeling.ipynb: Includes topics in notebook #1, and model development using hyperparameter tuning and cross-validation.
- pySpark-machine-learning-data-science-spark-model-consumption.ipynb: Shows how to operationalize a saved model using Python on HDInsight clusters.
Spark 2.0 notebooks
These notebooks are to be run in the pySpark3 kernel of Jupyter notebook server.
- Spark2.0-pySpark3-machine-learning-data-science-spark-advanced-data-exploration-modeling.ipynb: This file provides information on how to perform data exploration, modeling, and scoring in Spark 2.0 clusters using the NYC Taxi trip and fare data-set described here. This notebook may be a good starting point for quickly exploring the code we have provided for Spark 2.0. For a more detailed notebook analyzes the NYC Taxi data, see the next notebook in this list. See the notes following this list that compares these notebooks.
- Spark2.0-pySpark3_NYC_Taxi_Tip_Regression.ipynb: This file shows how to perform data wrangling (Spark SQL and dataframe operations), exploration, modeling and scoring using the NYC Taxi trip and fare data-set described here.
- Spark2.0-pySpark3_Airline_Departure_Delay_Classification.ipynb: This file shows how to perform data wrangling (Spark SQL and dataframe operations), exploration, modeling and scoring using the well-known Airline On-time departure dataset from 2011 and 2012. We integrated the airline dataset with the airport weather data (for example, windspeed, temperature, altitude etc.) prior to modeling, so these weather features can be included in the model.
The airline dataset was added to the Spark 2.0 notebooks to better illustrate the use of classification algorithms. See the following links for information about airline on-time departure dataset and weather dataset:
The Spark 2.0 notebooks on the NYC taxi and airline flight delay data-sets can take 10 mins or more to run (depending on the size of your HDI cluster). The first notebook in the above list shows many aspects of the data exploration, visualization and ML model training in a notebook that takes less time to run with down-sampled NYC data set, in which the taxi and fare files have been pre-joined: Spark2.0-pySpark3-machine-learning-data-science-spark-advanced-data-exploration-modeling.ipynb. This notebook takes a much shorter time to finish (2-3 mins) and may be a good starting point for quickly exploring the code we have provided for Spark 2.0.
For guidance on the operationalization of a Spark 2.0 model and model consumption for scoring, see the Spark 1.6 document on consumption for an example outlining the steps required. To use this example on Spark 2.0, replace the Python code file with this file.
The following procedures are related to Spark 1.6. For the Spark 2.0 version, use the notebooks described and linked to previously.
You must have an Azure subscription. If you do not already have one, see Get Azure free trial.
You need a Spark 1.6 cluster to complete this walkthrough. To create one, see the instructions provided in Get started: create Apache Spark on Azure HDInsight. The cluster type and version is specified from the Select Cluster Type menu.
For a topic that shows how to use Scala rather than Python to complete tasks for an end-to-end data science process, see the Data Science using Scala with Spark on Azure.
Billing for HDInsight clusters is prorated per minute, whether you use them or not. Be sure to delete your cluster after you finish using it. See how to delete an HDInsight cluster.
The NYC 2013 Taxi data
The NYC Taxi Trip data is about 20 GB of compressed comma-separated values (CSV) files (~48 GB uncompressed), comprising more than 173 million individual trips and the fares paid for each trip. Each trip record includes the pickup and dropoff location and time, anonymized hack (driver's) license number and medallion (taxi’s unique id) number. The data covers all trips in the year 2013 and is provided in the following two datasets for each month:
The 'trip_data' CSV files contain trip details, such as number of passengers, pick up and dropoff points, trip duration, and trip length. Here are a few sample records:
89D227B655E5C82AECF13C3F540D4CF4,BA96DE419E711691B9445D6A6307C170,CMT,1,N,2013-01-01 15:11:48,2013-01-01 15:18:10,4,382,1.00,-73.978165,40.757977,-73.989838,40.751171
0BD7C8F5BA12B88E0B67BED28BEA73D8,9FD8F69F0804BDB5549F40E9DA1BE472,CMT,1,N,2013-01-06 00:18:35,2013-01-06 00:22:54,1,259,1.50,-74.006683,40.731781,-73.994499,40.75066
0BD7C8F5BA12B88E0B67BED28BEA73D8,9FD8F69F0804BDB5549F40E9DA1BE472,CMT,1,N,2013-01-05 18:49:41,2013-01-05 18:54:23,1,282,1.10,-74.004707,40.73777,-74.009834,40.726002
DFD2202EE08F7A8DC9A57B02ACB81FE2,51EE87E3205C985EF8431D850C786310,CMT,1,N,2013-01-07 23:54:15,2013-01-07 23:58:20,2,244,.70,-73.974602,40.759945,-73.984734,40.759388
DFD2202EE08F7A8DC9A57B02ACB81FE2,51EE87E3205C985EF8431D850C786310,CMT,1,N,2013-01-07 23:25:03,2013-01-07 23:34:24,1,560,2.10,-73.97625,40.748528,-74.002586,40.747868
The 'trip_fare' CSV files contain details of the fare paid for each trip, such as payment type, fare amount, surcharge and taxes, tips and tolls, and the total amount paid. Here are a few sample records:
medallion, hack_license, vendor_id, pickup_datetime, payment_type, fare_amount, surcharge, mta_tax, tip_amount, tolls_amount, total_amount
We have taken a 0.1% sample of these files and joined the trip_data and trip_fare CVS files into a single dataset to use as the input dataset for this walkthrough. The unique key to join trip_data and trip_fare is composed of the fields: medallion, hack_licence and pickup_datetime. Each record of the dataset contains the following attributes representing a NYC Taxi trip:
|medallion||Anonymized taxi medallion (unique taxi id)|
|hack_license||Anonymized Hackney Carriage License number|
|vendor_id||Taxi vendor id|
|rate_code||NYC taxi rate of fare|
|store_and_fwd_flag||Store and forward flag|
|pickup_datetime||Pick up date & time|
|dropoff_datetime||Dropoff date & time|
|pickup_hour||Pick up hour|
|pickup_week||Pick up week of the year|
|weekday||Weekday (range 1-7)|
|passenger_count||Number of passengers in a taxi trip|
|trip_time_in_secs||Trip time in seconds|
|trip_distance||Trip distance traveled in miles|
|pickup_longitude||Pick up longitude|
|pickup_latitude||Pick up latitude|
|direct_distance||Direct distance between pickup and dropoff locations|
|payment_type||Payment type (cash, credit-card etc.)|
|fare_amount||Fare amount in|
|mta_tax||MTA Metro Transportation tax|
|tipped||Tipped (0/1 for no or yes)|
|tip_class||Tip class (0: $0, 1: $0-5, 2: $6-10, 3: $11-20, 4: > $20)|
Execute code from a Jupyter notebook on the Spark cluster
You can launch the Jupyter Notebook from the Azure portal. Find your Spark cluster on your dashboard and click it to enter management page for your cluster. To open the notebook associated with the Spark cluster, click Cluster Dashboards -> Jupyter Notebook.
You can also browse to
https://CLUSTERNAME.azurehdinsight.net/jupyter to access the Jupyter Notebooks. Replace the CLUSTERNAME part of this URL with the name of your own cluster. You need the password for your admin account to access the notebooks.
Select PySpark to see a directory that contains a few examples of pre-packaged notebooks that use the PySpark API. The notebooks that contain the code samples for this suite of Spark topic are available at GitHub
You can upload the notebooks directly from GitHub to the Jupyter notebook server on your Spark cluster. On the home page of your Jupyter, click the Upload button on the right part of the screen. It opens a file explorer. Here you can paste the GitHub (raw content) URL of the Notebook and click Open.
You see the file name on your Jupyter file list with an Upload button again. Click this Upload button. Now you have imported the notebook. Repeat these steps to upload the other notebooks from this walkthrough.
You can right-click the links on your browser and select Copy Link to get the GitHub raw content URL. You can paste this URL into the Jupyter Upload file explorer dialog box.
Now you can:
- See the code by clicking the notebook.
- Execute each cell by pressing SHIFT-ENTER.
- Run the entire notebook by clicking on Cell -> Run.
- Use the automatic visualization of queries.
The PySpark kernel automatically visualizes the output of SQL (HiveQL) queries. You are given the option to select among several different types of visualizations (Table, Pie, Line, Area, or Bar) by using the Type menu buttons in the notebook:
Now that you are set up with an HDInsight Spark cluster and have uploaded the Jupyter notebooks, you are ready to work through the topics that correspond to the three PySpark notebooks. They show how to explore your data and then how to create and consume models. The advanced data exploration and modeling notebook shows how to include cross-validation, hyper-parameter sweeping, and model evaluation.
Data Exploration and modeling with Spark: Explore the dataset and create, score, and evaluate the machine learning models by working through the Create binary classification and regression models for data with the Spark MLlib toolkit topic.
Model consumption: To learn how to score the classification and regression models created in this topic, see Score and evaluate Spark-built machine learning models.
Cross-validation and hyperparameter sweeping: See Advanced data exploration and modeling with Spark on how models can be trained using cross-validation and hyper-parameter sweeping