FiftyOne Code Style

Module Template

python

"""
Module description.

| Copyright 2017-2026, 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)

python

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:

python

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:

python

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:

python

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`