Introduction to Contextual Bandits and Reinforcement Learning.

What are Contextual Bandits?

As demand for features such as customization systems, fast information retrieval, and anomaly detection rises, so there is a need for a solution to maximise these characteristics. Contextual bandit is a machine learning framework developed to deal with these and other difficult circumstances.

A learning system can use contextual bandits to test out multiple behaviours and automatically learn which one has the most rewarding outcome for a particular circumstance.

It is a strong, generalizable method to address critical business demands in industries ranging from healthcare to finance, and nearly everything in between.

Contextual bandits allow you to pick which material to display to the user, rank advertising, improve search results, choose the best image to display on the page, and much more.

Multi Armed Bandit Problems

A multi-armed bandit approach uses machine learning techniques to dynamically distribute traffic to variants that perform well while assigning less traffic to variants that perform badly.

Because there is no need to wait for a single winning variant, multi-armed bandits should yield speedier results.

The term “bandit” in “multi-armed bandits” is derived from “one-armed bandit” devices seen in casinos. Assume you’re at a casino with a lot of one-armed bandit machines. Each machine has a distinct chance of winning. Your objective is to maximise the overall payment.

The challenge is a compromise between exploration and exploitation. you should balance attempting multiple bandits to learn more about the anticipated payment of each machine, but you also need to exploit the best bandit to know  more about it.

Many real-world applications exist for these contextual bandits , including website optimization, clinical trials, adaptive routing, and financial portfolio creation.

Is Reinforcement learning an extent of contextual learning?

Reinforcement learning is the process of teaching machine learning models to make a series of judgments.In an uncertain, possibly complicated environment, the agent learns to attain a goal. Artificial intelligence is put in a game-like setting in reinforcement learning.

Reinforcement learning algorithms come in a variety of flavours. Deep reinforcement learning is one of the reinforcement learning extensions. As part of the system, it employs a deep neural network.

Is the A/B testing outdated?

According to statistics  70% of clients are interested in sales and 30% in organic materials, we may discover that the winning version is a sales banner. We may opt to utilise that variation for the whole client base after we finish testing.

However, by doing so, you have simply misinterpreted 30% of your consumers and shown them something they are uninterested in. Furthermore, you passed up an opportunity to steer customers toward items made from sustainable resources, which might have a significantly larger profit margin.

Contextual Bandits automatically handle situations like these. They rephrase the AB test question (What variation works best for everyone) to ask: To which segment should it display this variant?

How do contextual bandits function on AutoML Tables?

We were able to construct a contextual bandit model pipeline that performs as well as or better than previous models using Google Cloud AutoML Tables, without the requirement for an expert for tweaking or feature engineering.

Users with no machine learning experience may use AutoML Tables to quickly train a model using a contextual bandit method. It accomplishes this by using:

  • The raw input data is subjected to automated feature engineering.
  • Search-based hyper-parameter tuning
  • Model Selection is the process of advancing models that have shown promise to the next level.
  • Tuning and Assembling the Model

In “AutoML for Contextual Bandits,” we compared our bandit model driven by AutoML Tables to earlier work using various data sources.

The performance of the model was compared to that of other models on various well-known datasets where the contextual bandit technique has been used. These datasets, which have been utilised in previous well-known work in the field, aim to test contextual bandit models on a variety of applications, including chess and data from telescopes.


Contextual bandits is an interesting technique for addressing the complex challenges that businesses face today, and AutoML Tables makes it accessible to a wide range of organizations, while also performing exceptionally well.

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