Agent skill
fiftyone-code-style
Write Python code following FiftyOne's official conventions. Use when contributing to FiftyOne, developing plugins, or writing code that integrates with FiftyOne's codebase.
Install this agent skill to your Project
npx add-skill https://github.com/aiskillstore/marketplace/tree/main/skills/adonaivera/fiftyone-code-style
SKILL.md
FiftyOne Code Style
Module Template
"""
Module description.
| Copyright 2017-2025, Voxel51, Inc.
| `voxel51.com <https://voxel51.com/>`_
|
"""
# Standard library
import logging
import os
# Third-party
import numpy as np
# eta (Voxel51 utilities)
import eta.core.utils as etau
# FiftyOne
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 (underscore prefix)."""
return arg
Import Organization
Four groups, alphabetized within each:
| Group | Example |
|---|---|
| 1. Standard library | import logging, import os |
| 2. Third-party | import numpy as np, from PIL import Image |
| 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)
Function Docstring
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
"""
Class Docstring
class ImageMetadata(Metadata):
"""Class for storing metadata about image samples.
Args:
size_bytes (None): the size of the image on disk, in bytes
mime_type (None): the MIME type of the image
width (None): the width of the image, in pixels
height (None): the height of the image, in pixels
"""
Key patterns:
- Args with defaults:
param (default): description - Multi-line descriptions: indent continuation
- Cross-references:
:class:fiftyone.module.Class``
Private Functions
# Public API delegates to private helper
def build_for(cls, path_or_url, mime_type=None):
"""Builds a Metadata object for the given file."""
if path_or_url.startswith("http"):
return cls._build_for_url(path_or_url, mime_type=mime_type)
return cls._build_for_local(path_or_url, mime_type=mime_type)
# Private: underscore prefix, focused purpose
def _build_for_local(cls, filepath, mime_type=None):
"""Internal helper for local files."""
size_bytes = os.path.getsize(filepath)
if mime_type is None:
mime_type = etau.guess_mime_type(filepath)
return cls(size_bytes=size_bytes, mime_type=mime_type)
Lazy Imports
Use fou.lazy_import() for optional/heavy dependencies:
# Basic lazy import
o3d = fou.lazy_import("open3d", callback=lambda: fou.ensure_package("open3d"))
# With ensure_import for pycocotools
mask_utils = fou.lazy_import(
"pycocotools.mask", callback=lambda: fou.ensure_import("pycocotools")
)
# Internal module lazy import
fop = fou.lazy_import("fiftyone.core.plots.plotly")
When to use:
- Heavy packages (open3d, tensorflow, torch)
- Optional dependencies (pycocotools)
- Circular import prevention
Guard Patterns
Use hasattr() for conditional behavior:
# Check for optional attribute
if hasattr(label, "confidence"):
if label.confidence is None or label.confidence < threshold:
label = label.__class__()
# Check for config attribute
if hasattr(eval_info.config, "iscrowd"):
crowd_attr = eval_info.config.iscrowd
else:
crowd_attr = None
# Dynamic state initialization
if not hasattr(pb, "_next_idx"):
pb._next_idx = 0
pb._next_iters = []
Error Handling
Use logger.warning() for non-fatal errors:
# Non-fatal: warn and continue
try:
for target in fo.config.logging_debug_targets.split(","):
if logger_name := target.strip():
loggers.append(logging.getLogger(logger_name))
except Exception as e:
logger.warning(
"Failed to parse logging debug targets '%s': %s",
fo.config.logging_debug_targets,
e,
)
# Missing optional import
try:
import resource
except ImportError as e:
if warn_on_failure:
logger.warning(e)
return
# Graceful fallback
try:
mask = etai.render_instance_image(dobj.mask, dobj.bounding_box, frame_size)
except:
width, height = frame_size
mask = np.zeros((height, width), dtype=bool)
Avoid Redundant Implementations
Before writing new functions, check if FiftyOne already provides the functionality.
Common Utilities in fiftyone.core.utils (fou)
| Function | Purpose |
|---|---|
fou.lazy_import() |
Lazy module loading |
fou.ensure_package() |
Install missing package |
fou.ensure_import() |
Verify import available |
fou.extract_kwargs_for_class() |
Split kwargs for class |
fou.load_xml_as_dict() |
Parse XML to dict |
fou.get_default_executor() |
Get thread pool executor |
Common Utilities in eta.core.utils (etau)
| Function | Purpose |
|---|---|
etau.guess_mime_type() |
Detect file MIME type |
etau.is_str() |
Check if string |
etau.ensure_dir() |
Create directory if missing |
etau.ensure_basedir() |
Create parent directory |
etau.make_temp_dir() |
Create temp directory |
Before Writing New Code
-
Search existing modules for similar functionality:
bashgrep -r "def your_function_name" fiftyone/ grep -r "similar_keyword" fiftyone/core/utils.py -
Check these modules first:
fiftyone.core.utils- General utilitiesfiftyone.core.storage- File/cloud operationsfiftyone.utils.*- Format-specific utilitieseta.core.utils- Low-level helpers
-
Red flags for redundancy:
- File path manipulation → check
os.pathoretau - JSON/dict operations → check
eta.core.serial - Image operations → check
fiftyone.utils.image - Type checking → check
etau.is_str(), etc.
- File path manipulation → check
Code Validation Checklist
Before submitting code, verify:
Style Compliance
- Module has copyright header docstring
- Imports in 4 groups (stdlib → third-party → eta → fiftyone)
- Imports alphabetized within groups
- FiftyOne imports use standard aliases (fol, fou, etc.)
- Logger defined as
logger = logging.getLogger(__name__) - Google-style docstrings with Args/Returns/Raises
- Private functions prefixed with
_
Code Quality
- No redundant implementations (checked existing utils)
- Heavy imports use
fou.lazy_import() - Optional attributes use
hasattr()guards - Non-fatal errors use
logger.warning() - No bare
except:(specify exception type when possible)
Testing
# Run linting
pylint fiftyone/your_module.py
# Check style
black --check fiftyone/your_module.py
# Run tests
pytest tests/unittests/your_test.py -v
Quick Reference
| Pattern | Convention |
|---|---|
| Module structure | Docstring → imports → logger → public → private → classes |
| Private functions | _prefix, module-level, small & focused |
| Docstrings | Google-style with Args/Returns/Raises |
| Error handling | try/except + logger.warning() for non-fatal |
| Lazy imports | fou.lazy_import() for optional deps |
| Guard patterns | hasattr() checks for conditional behavior |
| Import aliases | fol, fof, fom, fos, fou |
| Constants | UPPERCASE, private: _UPPERCASE |
| Class inheritance | Explicit class Foo(object): |
| Redundancy check | Search fou, etau, existing modules first |
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