---
title: "ClassDescriptionMapElem"
---
<!-- DO NOT EDIT! This file was auto-generated by crates/build/re_types_builder/src/codegen/docs/website.rs -->

⚠️ **This type is _unstable_ and may change significantly in a way that the data won't be backwards compatible.**
A helper type for mapping [`datatypes.ClassId`](https://rerun.io/docs/reference/types/datatypes/class_id)s to class descriptions.

This is internal to [`components.AnnotationContext`](https://rerun.io/docs/reference/types/components/annotation_context).

## Fields
#### `class_id`
Type: non-null [`ClassId`](../datatypes/class_id.md)

The key: the [`components.ClassId`](https://rerun.io/docs/reference/types/components/class_id).

#### `class_description`
Type: non-null [`ClassDescription`](../datatypes/class_description.md)

The value: class name, color, etc.


## Arrow datatype
```
Struct(
    "class_id": non-null UInt16
    "class_description": non-null Struct(
        "info": non-null Struct(
            "id": non-null UInt16
            "label": Utf8
            "color": UInt32
        )
        "keypoint_annotations": non-null List(non-null Struct(
                "id": non-null UInt16
                "label": Utf8
                "color": UInt32
            ))
        "keypoint_connections": non-null List(non-null Struct(
                "keypoint0": non-null UInt16
                "keypoint1": non-null UInt16
            ))
    )
)
```

## API reference links
 * 🌊 [C++ API docs for `ClassDescriptionMapElem`](https://ref.rerun.io/docs/cpp/stable/structrerun_1_1datatypes_1_1ClassDescriptionMapElem.html)
 * 🐍 [Python API docs for `ClassDescriptionMapElem`](https://ref.rerun.io/docs/python/stable/common/datatypes#rerun.datatypes.ClassDescriptionMapElem)
 * 🦀 [Rust API docs for `ClassDescriptionMapElem`](https://docs.rs/rerun/latest/rerun/datatypes/struct.ClassDescriptionMapElem.html)


## Used by

* [`AnnotationContext`](../components/annotation_context.md)
