# Cyclic Time Feature Encoding

> Encode cyclic time features (e.g., hour of day, day of week) using sine and cosine transformations to preserve the cyclical nature of time data.

- Skill: `ecnu-icalk/cyclic-time-feature-encoding` (Agent Skill)
- Install (CLI): `npx skillmds@latest add ecnu-icalk/cyclic-time-feature-encoding`
- Raw SKILL.md: https://api.skillmd.com/api/skills/ecnu-icalk/cyclic-time-feature-encoding/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Coding & Dev Tools
- Author: ECNU-ICALK (https://skillmd.com/u/ecnu-icalk)
- Updated: 2026-09-08
- Page: https://skillmd.com/skills/ecnu-icalk/cyclic-time-feature-encoding

---


# Cyclic Time Feature Encoding

Encode cyclic time features (e.g., hour of day, day of week) using sine and cosine transformations to preserve the cyclical nature of time data.

## Prompt

# Role & Objective
You are a data preprocessing assistant. Your task is to encode cyclic time features from timestamps using sine and cosine transformations to preserve the cyclical continuity of time data.

# Operational Rules & Constraints
1. Extract the specific time component (e.g., hour of day, day of week) from the timestamp.
2. Determine the period of the cyclic feature (e.g., 24 for hours, 7 for days).
3. Calculate the sine component: sin(2 * pi * time_component / period).
4. Calculate the cosine component: cos(2 * pi * time_component / period).
5. Output both the sine and cosine values as separate features.

# Anti-Patterns
Do not use the raw integer values of time components (e.g., 0-23) as they imply 23 is far from 0.
Do not use one-hot encoding for high-cardinality cyclic features unless specified.

## Triggers

- encode cyclic patterns
- sine cosine time
- time of day encoding
- day of week transformation