DateParts

Use DateParts when calendar position matters more than timestamp magnitude: hour of day, day of week, month of year, and related cyclical buckets.

{
  "created_at": "2026-05-28T14:30:00"
}

import json2vec as j2v

created_at = j2v.DateParts(
    "created_at",
    dateparts=["day of week", "HourOfDay"],
    pattern="%Y-%m-%dT%H:%M:%S",
)

Use DateParts for recurrence and seasonality: hour of day, day of week, month, business cycles, and operational schedules. Use a derived Number for elapsed time, age, recency, duration, or ordering. For example, compute days_since_transaction before inference when the signal is the difference between inference time and transaction time.

Need	Prefer
Hour, weekday, month, or seasonal recurrence	DateParts
Age, duration, recency, or ordering	derived Number
Request-time-dependent windows	preprocessor plus Number

Avoid raw timestamps as features by default. They can encourage the model to learn dataset-specific time boundaries, rollout dates, policy changes, or train/test split artifacts instead of general patterns.

Input Values

DateParts accepts datetime-like values that NumPy can coerce to datetime64[m]. If pattern is provided, source values are parsed with datetime.strptime first. None is encoded as a null state, and missing array positions are encoded as padded state.

Internal precision is minutes. Seconds can be parsed, but no built-in date part uses second-level precision.

Examples

Common date-part fields include:

• Transaction time, login time, request time, or event time.
• Seasonal features such as month of year or day of year.
• Operational cycles such as hour of day, day of week, or minute of hour.
• Calendar-position signals where exact elapsed time is less important than recurrence.

Configuration

Option	Default	Notes
dateparts	required	Non-empty, unique list of date parts to extract. Friendly casing and separators are normalized.
pattern	None	Optional datetime.strptime pattern for string inputs.

Available date parts:

Date part	Buckets
Day Of Year	366
Week Of Year	53
Month Of Year	12
Day Of Month	31
Week Of Month	6
Day Of Week	7
Hour Of Day	24
Minute Of Hour	60

dateparts accepts common spellings such as "day_of_week", "day of week", "Day-Of-Week", "DAY_OF_WEEK", and "DayOfWeek". Serialized schemas use the canonical lower-case values.

Target Behavior

When DateParts is masked or used as a target, the decoder predicts:

• state: probabilities for valued, null, padded, and masked.
• content: one categorical distribution for each configured date part.

The loss averages the configured date-part classification losses after the state loss.

Prediction Output

DateParts currently trains and reports losses and accuracies, but it does not emit decoded timestamp values in Model.predict(...). Configure it as an input feature or reconstruction target when the model should learn timestamp structure, not when you need decoded timestamp values. It can still contribute to model context and reconstruction losses. Configure embed=True when you want the field address to emit an embedding payload.

Notes

Use Number for monotonic timestamps, ages, intervals, or durations where numeric distance matters. DateParts discards that continuous distance and keeps only the requested calendar buckets.

Preprocess timestamps to a consistent timezone before encoding. json2vec stores dateparts at minute precision and does not apply an application-specific timezone policy.