Скачать или смотреть How to Resolve the "Object of type Int32MultiArray is not JSON serializable" Error

Learn how to resolve the "Object of type Int32MultiArray is not JSON serializable" error when working with JSON serialization, numpy arrays, ROS messages, and TCP.
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When working with data serialization in Python, especially in contexts involving JSON, numpy arrays, and ROS (Robot Operating System) messages, you may encounter the error: "Object of type Int32MultiArray is not JSON serializable". This error indicates that the serialization process you are using does not support out-of-the-box conversion for certain object types, such as numpy arrays or ROS message types, for example, Int32MultiArray.

Understanding the Problem

JSON (JavaScript Object Notation) is a lightweight data-interchange format that's easy for humans to read and write, and easy for machines to parse and generate. However, JSON natively supports only a limited set of data types: strings, numbers, objects (which map to dictionaries in Python), arrays (which map to lists in Python), booleans, and null. Numpy arrays and certain ROS message types like Int32MultiArray do not fit the predefined JSON format, leading to the serialization error.

Common Contexts for the Error

Numpy Arrays:

Numpy arrays are widely used for numerical computations in Python. They are efficient for large data sets but not inherently supported by JSON serialization.

Attempting to directly serialize numpy arrays results in an error: "Object of type ndarray is not JSON serializable".

ROS Messages:

ROS uses various types of message structures to communicate data between nodes.

Int32MultiArray is one of those message structures, comprising an array of 32-bit integers, which is not directly JSON serializable.

Solutions

Converting Numpy Arrays:

Convert numpy arrays to Python lists before serialization.

Use the tolist() method for numpy arrays:

[[See Video to Reveal this Text or Code Snippet]]

Converting ROS Messages:

Convert ROS messages to Python dictionaries or lists to enable JSON serialization.

Manually extract data from Int32MultiArray:

[[See Video to Reveal this Text or Code Snippet]]

Conclusion

The key to resolving the "Object of type Int32MultiArray is not JSON serializable" error lies in converting the non-serializable objects into a format that JSON can handle, such as Python lists or dictionaries. By ensuring that the data structures passed to the JSON serializer are compatible, you can avoid such errors and ensure seamless data interchange in applications involving JSON, numpy arrays, ROS messages, and TCP communication.