FiftyOne Code Style

Module Template

"""
Module description.

| Copyright 2017-2025, Voxel51, Inc.
| `voxel51.com <https://voxel51.com/>`_
|
"""
import logging
import os

import numpy as np

import eta.core.utils as etau

import fiftyone as fo
import fiftyone.core.fields as fof
import fiftyone.core.labels as fol
import fiftyone.core.utils as fou

logger = logging.getLogger(__name__)


def public_function(arg):
    """Public API function."""
    return _helper(arg)


def _helper(arg):
    """Private helper."""
    return arg

Import Organization

Four groups, alphabetized within each, separated by blank lines:

Group	Example
1. Standard library	import logging, import os
2. Third-party	import numpy as np
3. eta packages	import eta.core.utils as etau
4. FiftyOne	import fiftyone.core.labels as fol

FiftyOne Import Aliases

Module	Alias
fiftyone	fo
fiftyone.core.labels	fol
fiftyone.core.fields	fof
fiftyone.core.media	fom
fiftyone.core.storage	fos
fiftyone.core.utils	fou
fiftyone.utils.image	foui
fiftyone.utils.video	fouv

Docstrings (Google-Style)

def get_operator(operator_uri, enabled=True):
    """Gets the operator with the given URI.

    Args:
        operator_uri: the operator URI
        enabled (True): whether to include only enabled operators (True) or
            only disabled operators (False) or all operators ("all")

    Returns:
        an :class:`fiftyone.operators.Operator`

    Raises:
        ValueError: if the operator is not found
    """

Key patterns:

• Args with defaults: param (default): description
• Multi-line descriptions: indent continuation
• Cross-references: :class:fiftyone.module.Class``

Lazy Imports

Use fou.lazy_import() for optional/heavy dependencies:

o3d = fou.lazy_import("open3d", callback=lambda: fou.ensure_package("open3d"))

mask_utils = fou.lazy_import(
    "pycocotools.mask", callback=lambda: fou.ensure_import("pycocotools")
)

Guard Patterns

Use hasattr() for optional attributes:

if hasattr(label, "confidence"):
    if label.confidence is None or label.confidence < threshold:
        label = label.__class__()

Error Handling

Use logger.warning() for non-fatal errors:

try:
    result = process_data(data)
except Exception as e:
    logger.warning("Failed to process data: %s", e)

Avoid Redundant Code

Before writing new functions, search for existing implementations:

• Local: search the FiftyOne source if available in the environment
• Remote: search https://github.com/voxel51/fiftyone
• Check fiftyone/core/utils.py and fiftyone/utils/* first

Common Utilities

Module	Functions
fou	lazy_import(), ensure_package(), extract_kwargs_for_class()
etau	guess_mime_type(), ensure_dir(), make_temp_dir()

Quick Reference

Pattern	Convention
Module structure	Docstring → imports → logger → public → private
Private functions	_prefix
Docstrings	Google-style with Args/Returns/Raises
Error handling	logger.warning() for non-fatal
Lazy imports	fou.lazy_import() for optional deps
Guard patterns	hasattr() checks
Import aliases	fo, fol, fof, fom, fos, fou