..
 Copyright 2021 Graviti. Licensed under MIT License.
 
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 Common Label Properties
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Different types of labels contain different aspects of annotation information about the data.
Some are more general, and some are unique to a specific label type.

Three common properties of a label will be introduced first,
and the unique ones will be explained under the corresponding type of label.

Take a :doc:`2D box label </reference/label_format/Box2D>` as an example:

    >>> from tensorbay.label import LabeledBox2D
    >>> box2d_label = LabeledBox2D(
    ... 10, 20, 30, 40,
    ... category="<LABEL_CATEGORY>",
    ... attributes={"<LABEL_ATTRIBUTE_NAME>": "<LABEL_ATTRIBUTE_VALUE>"},
    ... instance="<LABEL_INSTANCE_ID>"
    ... )
    >>> box2d_label
    LabeledBox2D(10, 20, 30, 40)(
      (category): '<LABEL_CATEGORY>',
      (attributes): {...},
      (instance): '<LABEL_INSTANCE_ID>'
    )

category
========

Category is a string indicating the class of the labeled object.

    >>> box2d_label.category
    '<LABEL_CATEGORY>'

attributes
==========

Attributes are the additional information about this data,
and there is no limit on the number of attributes.

The attribute names and values are stored in key-value pairs.

   >>> box2d_label.attributes
   {'<LABEL_ATTRIBUTE_NAME>': '<LABEL_ATTRIBUTE_VALUE>'}


instance
========

Instance is the unique id for the object inside of the label,
which is mostly used for tracking tasks.

   >>> box2d_label.instance
   "<LABEL_INSTANCE_ID>"