An End-to-End AutoML Solution for Tabular Data at KaggleDays

Posted by Yifeng Lu, Software Engineer, Google AI

Machine learning (ML) for tabular data (e.g. spreadsheet data) is one of the most active research areas in both ML research and business applications. Solutions to tabular data problems, such as fraud detection and inventory prediction, are critical for many business sectors, including retail, supply chain, finance, manufacturing, marketing and others. Current ML-based solutions to these problems can be achieved by those with significant ML expertise, including manual feature engineering and hyper-parameter tuning, to create a good model. However, the lack of broad availability of these skills limits the efficiency of business improvements through ML.

Google’s AutoML efforts aim to make ML more scalable and accelerate both research and industry applications. Our initial efforts of neural architecture search have enabled breakthroughs in computer vision with NasNet, and evolutionary methods such as AmoebaNet and hardware-aware mobile vision architecture MNasNet further show the benefit of these learning-to-learn methods. Recently, we applied a learning-based approach to tabular data, creating a scalable end-to-end AutoML solution that meets three key criteria:

• Full automation: Data and computation resources are the only inputs, while a servable TensorFlow model is the output. The whole process requires no human intervention.
  
• Extensive coverage: The solution is applicable to the majority of arbitrary tasks in the tabular data domain.
  
• High quality: Models generated by AutoML has comparable quality to models manually crafted by top ML experts.
  

To benchmark our solution, we entered our algorithm in the KaggleDays SF Hackathon, an 8.5 hour competition of 74 teams with up to 3 members per team, as part of the KaggleDays event. The first time that AutoML has competed against Kaggle participants, the competition involved predicting manufacturing defects given information about the material properties and testing results for batches of automotive parts. Despite competing against participants thats were at the Kaggle progression system Master level, including many who were at the GrandMaster level, our team (“Google AutoML”) led for most of the day and ended up finishing second place by a narrow margin, as seen in the final leaderboard.

Our team’s AutoML solution was a multistage TensorFlow pipeline. The first stage is responsible for automatic feature engineering, architecture search, and hyperparameter tuning through search. The promising models from the first stage are fed into the second stage, where cross validation and bootstrap aggregating are applied for better model selection. The best models from the second stage are then combined in the final model.

The workflow for the “Google AutoML” team was quite different from that of other Kaggle competitors. While they were busy with analyzing data and experimenting with various feature engineering ideas, our team spent most of time monitoring jobs and and waiting for them to finish. Our solution for second place on the final leaderboard required 1 hour on 2500 CPUs to finish end-to-end.

After the competition, Kaggle published a public kernel to investigate winning solutions and found that augmenting the top hand-designed models with AutoML models, such as ours, could be a useful way for ML experts to create even better performing systems. As can be seen in the plot below, AutoML has the potential to enhance the efforts of human developers and address a broad range of ML problems.

Potential model quality improvement on final leaderboard if AutoML models were merged with other Kagglers’ models. “Erkut & Mark, Google AutoML”, includes the top winner “Erkut & Mark” and the second place “Google AutoML” models. Erkut Aykutlug and Mark Peng used XGBoost with creative feature engineering whereas AutoML uses both neural network and gradient boosting tree (TFBT) with automatic feature engineering and hyperparameter tuning.

Google Cloud AutoML Tables
The solution we presented at the competitions is the main algorithm in Google Cloud AutoML Tables, which was recently launched (beta) at Google Cloud Next ‘19. The AutoML Tables implementation regularly performs well in benchmark tests against Kaggle competitions as shown in the plot below, demonstrating state-of-the-art performance across the industry.

Third party benchmark of AutoML Tables on multiple Kaggle competitions

We are excited about the potential application of AutoML methods across a wide range of real business problems. Customers have already been leveraging their tabular enterprise data to tackle mission-critical tasks like supply chain management and lead conversion optimization using AutoML Tables, and we are excited to be providing our state-of-the-art models to solve tabular data problems.

Acknowledgements
This project was only possible thanks to Google Brain team members Ming Chen, Da Huang, Yifeng Lu, Quoc V. Le and Vishy Tirumalashetty. We also thank Dawei Jia, Chenyu Zhao and Tin-yun Ho from the Cloud AutoML Tables team for great infrastructure and product landing collaboration. Thanks to Walter Reade, Julia Elliott and Kaggle for organizing such an engaging competition.