# Custom Code Executor Agent Sample

This directory contains a sample agent that demonstrates how to customize a
`CodeExecutor` to perform environment setup before executing code. The specific
example shows how to add support for Japanese fonts in `matplotlib` plots by
subclassing `VertexAiCodeExecutor`.

## Overview

This sample showcases a powerful pattern for customizing code execution
environments. By extending a base `CodeExecutor`, you can inject setup code to
prepare the environment before a user's code is run. This enables advanced use
cases that require specific configurations, in this case, adding custom fonts.

## Key Concept: `CodeExecutor` Customization

The Agent Development Kit (ADK) allows for powerful customization of code
execution by extending existing `CodeExecutor` classes. By subclassing an
executor (e.g., `VertexAiCodeExecutor`) and overriding its `execute_code`
method, you can inject custom logic to:

-   Modify the code before it's executed.
-   Add files to the execution environment.
-   Process the results after execution.

## Example: Adding Japanese Font Support

The `CustomCodeExecutor` in this sample solves a common issue where non-Latin
characters do not render correctly in plots generated by `matplotlib` due to
missing fonts in the execution environment.

It achieves this by: 1. **Subclassing `VertexAiCodeExecutor`**: It inherits all
the functionality of the standard Vertex AI code executor. 2. **Overriding
`execute_code`**: Before calling the parent's `execute_code` method, it performs
the following steps: a. Downloads a Japanese font file (`NotoSerifJP`). b. Adds
the font file to the list of files to be uploaded to the execution environment.
c. Prepends a Python code snippet to the user's code. This snippet uses
`matplotlib.font_manager` to register the newly available font file, making it
available for plotting. 3. **Executing the modified code**: The combined code
(setup snippet + original code) is then executed in the Vertex AI environment,
which now has the Japanese font available for `matplotlib`.

This ensures that any plots generated during the agent's session can correctly
display Japanese characters.

## How to use

### Prerequisites

Ensure you have configured your environment for using
[Google Cloud Vertex AI](https://google.github.io/adk-docs/get-started/quickstart/#gemini---google-cloud-vertex-ai).
You will need to have a Google Cloud Project with the Vertex AI API enabled.

### Running the agent

You can run this agent using the ADK CLI.

To interact with the agent through the command line:

```bash
adk run contributing/samples/custom_code_execution "Plot a bar chart with these categories and values: {'リンゴ': 10, 'バナナ': 15, 'オレンジ': 8}. Title the chart '果物の在庫' (Fruit Stock)."
```

To use the web interface:

```bash
adk web contributing/samples/
```

Then select `custom_code_execution` from the list of agents and interact with
it.