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Exemplary Machine Learning Pipeline

Introduction

This repository aims to act as an exemplary data science & machine learning pipeline to any tabular data problem. Moreover, the notebooks aim to explore two Python packages for machine learning automation: featuretools and h2o. Whereas featuretools specializes in feature engineering, h2ospecializes in modelling.

Follow the notebooks in the order indicated. On a broader sense, here is what we cover:

  • Data Insights & Visualizations
  • Data Cleaning
  • Data Imputation
  • Manual Feature Engineering
  • Automated Feature Engineering via featuretools
  • Feature Scaling
  • Feature Selection
  • Feature Encoding
  • Modelling (Model Selection & Analysis) via h2o

There are two main arguments we can make:

  1. Currently, there is a huge gap between what we call automated machine learning and the actual machine learning workflow we have to create in order to solve a real data problem. This is a recurring theme in all notebooks as we had to try to impute missing values, apply feature selection, and much more in order to increase our prediction score.
  2. The existing gap is based on implementations, rather than theory. In other words, there is a great literature (papers, workshops, experiments, examples, notebooks, etc.) that has evolved around the missing points in this gap. The notebooks make the appropriate references. Essentially, the hard parts are covered by packages such as h2o and featuretools, but the easier parts are not addressed in terms of automation. Notice the word automation here, otherwise sklearn already has somewhat complete implementations related to the missing points mentioned in this repository.

Getting Started

Download the data folders with prepared training and testing data files (.csv) from here and replace them with their name-wise match in this repository. Or alternatively, you can only download (0)data/ (which you can also get from here) and run the Jupyter notebooks to generate rest of the data yourself.

Results & Comparisons

All of the below models are trained and validated by h2o's H2OAutoML module, but the operations applied to the data before the modelling process differs for each row. For fairness of comparison, all models are trained under the time limit of 10000 seconds and with similar parameters.

Data Directory Data & Operations Description Num Features Best Model Maximum Prediction Accuracy (%)
(0)data Untouched files extracted from Kaggle 13 Stacked Ensemble 56.19
(1)data_manual_ops Applied data imputation, removed nonsensical (outlier-like) values from 'age' column, and included a new feature engineered column by linking train_users.csv and age_gender_bkts.csv 14 Stacked Ensemble 62.54
(2)data_automated_ops Applied automated feature engineering via featuretools and by linking train_users.csv with sessions.csv and age_gender_bkts.csv. 137 XGBoost 68.85
(3)data_trimmed/raw (^) Applied manual feature scaling based on normal distribution for numerical variables and applied a comprehensive feature selection. 39 XGBoost 71.58
(3)data_trimmed/raw Same operations and data as (^), but applied undersampling to majority classes via h2o. 39 XGBoost 71.44
(3)data_trimmed/label_encoded Same operations and data as (^), but applied label encoding to all categorical variables. Hence, all variables are numeric in the end. 39 Stacked Ensemble 72.10

Future Work

  • Check Driverless AI Platform.
  • Look into more parameters of H2OAutoML module, and particularly try increasing the value of parameter @max_runtime_secs for longer training duration and hopefully better prediction scores.
  • Produce more self-encoded data.

Check to see if these increase prediction scores in any way.