gradio/components/label.py

"""gr.Label() component."""

from __future__ import annotations

import json
import operator
from collections.abc import Callable, Sequence
from pathlib import Path
from typing import TYPE_CHECKING, Any, Optional, Union

from gradio_client.documentation import document

from gradio.components.base import Component
from gradio.data_classes import GradioModel
from gradio.events import Events

if TYPE_CHECKING:
    from gradio.components import Timer


class LabelConfidence(GradioModel):
    label: Optional[Union[str, int, float]] = None
    confidence: Optional[float] = None


class LabelData(GradioModel):
    label: Optional[Union[str, int, float]] = None
    confidences: Optional[list[LabelConfidence]] = None


@document()
class Label(Component):
    """
    Displays a classification label, along with confidence scores of top categories, if provided. As this component does not
    accept user input, it is rarely used as an input component.

    Guides: image-classification-in-pytorch, image-classification-in-tensorflow, image-classification-with-vision-transformers
    """

    CONFIDENCES_KEY = "confidences"
    data_model = LabelData
    EVENTS = [Events.change, Events.select]

    def __init__(
        self,
        value: dict[str, float] | str | float | Callable | None = None,
        *,
        num_top_classes: int | None = None,
        label: str | None = None,
        every: Timer | float | None = None,
        inputs: Component | Sequence[Component] | set[Component] | None = None,
        show_label: bool | None = None,
        container: bool = True,
        scale: int | None = None,
        min_width: int = 160,
        visible: bool = True,
        elem_id: str | None = None,
        elem_classes: list[str] | str | None = None,
        render: bool = True,
        key: int | str | None = None,
        color: str | None = None,
    ):
        """
        Parameters:
            value: Default value to show in the component. If a str or number is provided, simply displays the string or number. If a {Dict[str, float]} of classes and confidences is provided, displays the top class on top and the `num_top_classes` below, along with their confidence bars. If callable, the function will be called whenever the app loads to set the initial value of the component.
            num_top_classes: number of most confident classes to show.
            label: the label for this component. Appears above the component and is also used as the header if there are a table of examples for this component. If None and used in a `gr.Interface`, the label will be the name of the parameter this component is assigned to.
            every: Continously calls `value` to recalculate it if `value` is a function (has no effect otherwise). Can provide a Timer whose tick resets `value`, or a float that provides the regular interval for the reset Timer.
            inputs: Components that are used as inputs to calculate `value` if `value` is a function (has no effect otherwise). `value` is recalculated any time the inputs change.
            show_label: if True, will display label.
            container: If True, will place the component in a container - providing some extra padding around the border.
            scale: relative size compared to adjacent Components. For example if Components A and B are in a Row, and A has scale=2, and B has scale=1, A will be twice as wide as B. Should be an integer. scale applies in Rows, and to top-level Components in Blocks where fill_height=True.
            min_width: minimum pixel width, will wrap if not sufficient screen space to satisfy this value. If a certain scale value results in this Component being narrower than min_width, the min_width parameter will be respected first.
            visible: If False, component will be hidden.
            elem_id: An optional string that is assigned as the id of this component in the HTML DOM. Can be used for targeting CSS styles.
            elem_classes: An optional list of strings that are assigned as the classes of this component in the HTML DOM. Can be used for targeting CSS styles.
            render: If False, component will not render be rendered in the Blocks context. Should be used if the intention is to assign event listeners now but render the component later.
            key: if assigned, will be used to assume identity across a re-render. Components that have the same key across a re-render will have their value preserved.
            color: The background color of the label (either a valid css color name or hexadecimal string).
        """
        self.num_top_classes = num_top_classes
        self.color = color
        super().__init__(
            label=label,
            every=every,
            inputs=inputs,
            show_label=show_label,
            container=container,
            scale=scale,
            min_width=min_width,
            visible=visible,
            elem_id=elem_id,
            elem_classes=elem_classes,
            render=render,
            key=key,
            value=value,
        )

    def preprocess(
        self, payload: LabelData | None
    ) -> dict[str, float] | str | int | float | None:
        """
        Parameters:
            payload: An instance of `LabelData` containing the label and confidences.
        Returns:
            Depending on the value, passes the label as a `str | int | float`, or the labels and confidences as a `dict[str, float]`.
        """
        if payload is None:
            return None
        if payload.confidences is None:
            return payload.label
        return {
            d["label"]: d["confidence"] for d in payload.model_dump()["confidences"]
        }

    def postprocess(
        self, value: dict[str | float, float] | str | int | float | None
    ) -> LabelData | dict | None:
        """
        Parameters:
            value: Expects a `dict[str, float]` of classes and confidences, or `str` with just the class or an `int | float` for regression outputs, or a `str` path to a .json file containing a json dictionary in one of the preceding formats.
        Returns:
            Returns a `LabelData` object with the label and confidences, or a `dict` of the same format, or a `str` or `int` or `float` if the input was a single label.
        """
        if value is None or value == {}:
            return {}
        if isinstance(value, str) and value.endswith(".json") and Path(value).exists():
            return LabelData(**json.loads(Path(value).read_text()))
        if isinstance(value, (str, float, int)):
            return LabelData(label=str(value))
        if isinstance(value, dict):
            if "confidences" in value and isinstance(value["confidences"], dict):
                value = value["confidences"]
                value = {c["label"]: c["confidence"] for c in value}
            sorted_pred = sorted(
                value.items(), key=operator.itemgetter(1), reverse=True
            )
            if self.num_top_classes is not None:
                sorted_pred = sorted_pred[: self.num_top_classes]
            return LabelData(
                label=sorted_pred[0][0],
                confidences=[
                    LabelConfidence(label=pred[0], confidence=pred[1])
                    for pred in sorted_pred
                ],
            )
        raise ValueError(
            "The `Label` output interface expects one of: a string label, or an int label, a "
            "float label, or a dictionary whose keys are labels and values are confidences. "
            f"Instead, got a {type(value)}"
        )

    def example_payload(self) -> Any:
        return {
            "label": "Cat",
            "confidences": [
                {"label": "cat", "confidence": 0.9},
                {"label": "dog", "confidence": 0.1},
            ],
        }

    def example_value(self) -> Any:
        return {"cat": 0.9, "dog": 0.1}