TargetFormatter¶

class flash.core.data.utilities.classification.TargetFormatter(labels=None, num_classes=None)[source]¶

A TargetFormatter is used to convert targets of a given type to a standard format required by the loss function. To implement a custom TargetFormatter, simply override the format method with your own logic.

Examples

>>> from dataclasses import dataclass
>>> from typing import ClassVar, Optional
>>> from flash.core.data.utilities.classification import TargetFormatter
>>>
>>> @dataclass
... class CustomStringTargetFormatter(TargetFormatter):
...     "A ``TargetFormatter`` which converts strings of the format '#<index>' to integers."
...     multi_label: ClassVar[Optional[bool]] = False
...     def format(self, target: str) -> int:
...         return int(target.strip("#"))
...
>>> formatter = CustomStringTargetFormatter()
>>> formatter("#1")
1