nrcd 0.1.3

Standardize cross country, track, and road-race times with NRCD formulas (weather, grade, altitude, distance, indoor track, and more).

nrcd

Python library for National Running Club Database (NRCD) performance standardization (cross country, track, road race). Implements the formulas documented in the NRCD paper preprint (not yet officially published; arXiv preprint forthcoming).

Use this to standardize your own race results — no NRCD dataset download required.

Quick start

Times can be seconds or clock strings ("22:15", "4:12.00", "10.52"). XC distances accept m/km/mi or labels like "5k". Invalid time, distance, or unit strings raise ValueError with a short hint (they do not return NaN silently).

Cross country — pass a target distance when you want a Riegel conversion (e.g. 8000m). Without it, the standardized time stays at the race distance.

Cross country — 5K in 22:15, target distance 8000m

from nrcd.standardize import format_time, standardize_xc

std = standardize_xc(
    "22:15",
    gender="M",
    reported_distance="5k",
    target_distance_m=8000,  # 8000m
    # target_distance="8k",
    # target_distance=8, target_distance_unit="km",
    # target_distance=4.97, target_distance_unit="mi",  # ~8000m
)
print(format_time(std))
# → 36:31.94

Cross country — 8 km with weather, grade, altitude, target distance 8000m

from nrcd.standardize import format_time, standardize_xc

std = standardize_xc(
    "27:30",
    gender="M",
    reported_distance=8,
    distance_unit="km",
    actual_distance=8.01,
    temperature=72,          # °F (default)
    dew_point=65,
    elevation_gain=2.5,      # % grade (default)
    elevation_loss=2.5,
    meet_elevation=5200,     # feet (default)
    target_distance_m=8000,  # 8000m
)
print(format_time(std))
# → 26:42.19

Outdoor track — 100m with wind

from nrcd.standardize import standardize_outdoor_track

std = standardize_outdoor_track(
    "13.52",
    gender="F",
    event_name="100m",
    wind_mps=2.0,
)
print(f"{std:.3f} s")
# → 13.630 s

Indoor track — 200m on a banked 200m oval

from nrcd.standardize import standardize_indoor_track

std = standardize_indoor_track(
    "21.80",
    gender="M",
    event_name="200m",
    lap_length_m=200,
    banked=True,
)
print(f"{std:.3f} s")
# → 22.588 s

Road — half marathon with weather and grade

from nrcd.standardize import format_time, standardize_road

std = standardize_road(
    "1:25:30",
    gender="F",
    event_name="Half Marathon",
    temperature=55,
    dew_point=48,
    elevation_gain=1.2,
    elevation_loss=1.2,
)
print(format_time(std))
# → 1:25:40.54 (same event distance; no Riegel target conversion)

Pipelines

Sport	Function	What differs
Cross country	standardize_xc	Weather, grade, altitude; optional Riegel to a target distance (e.g. 8000m)
Road	standardize_road	Same weather / grade / altitude as XC; distance from event_name; no Riegel target
Outdoor track	standardize_outdoor_track	Sprint wind, weather, grade, altitude
Indoor track	standardize_indoor_track	Lap/bank venue factors; no wind

standardize_result remains available when you need a custom sport_name string.

Factor breakdown — see why a time changed (weather, grade, altitude, wind, Riegel):

from nrcd.standardize import format_time, standardize_xc_detail

detail = standardize_xc_detail(
    "27:30",
    gender="M",
    reported_distance=8,
    distance_unit="km",
    temperature=72,
    dew_point=65,
    elevation_gain=2.5,
    elevation_loss=2.5,
    meet_elevation=5200,
    target_distance_m=8000,
)
print(format_time(detail.std_sec))
for step in detail.steps:
    print(step.name, step.factor, step.note or "")
# weather 0.98…  |  grade 1.02…  |  altitude …  |  target_distance … (8000m → 8000m)

Use standardize_result_detail for track/road (includes wind on outdoor sprints) or standardize_seconds_detail(ctx) from a RaceContext.

Batch — standardize many rows (pip install "nrcd[data]"):

from nrcd.standardize import standardize_dataframe

out = standardize_dataframe(df)  # adds std_time_sec
out = standardize_dataframe(df, detail=True)  # also std_detail per row

# Backfill weather/altitude then standardize (pip install "nrcd[data,apis]")
out = standardize_dataframe(df, enrich=True)

Column names map to RaceContext fields automatically (result_time → time_str, altitude → meet_elevation, meet_city → city, etc.). Override with column_map={"time_str": "result_time"}.

Rows at the same meet (same city/date/start time) share the enrich cache — 100 results trigger one weather API lookup, not 100. Or enrich only:

from nrcd.standardize import enrich_dataframe

df = enrich_dataframe(df, fetch_altitude=False)  # weather only

# Track API calls (cache misses only; same meet → one OpenWeather lookup)
from nrcd.standardize import DataframeBatchResult, enrich_dataframe

result = enrich_dataframe(df, return_usage=True)
assert isinstance(result, DataframeBatchResult)
print(result.api_usage.to_dict())  # openweather_geocode, openweather_timemachine, openweather_total, …

Unit switches (optional kwargs on all pipelines):

Field	Default	Alternative
temperature, dew_point	°F	temp_unit="C"
meet_elevation	feet	venue_elevation_unit="m"
elevation_gain, elevation_loss	% grade	grade_input="feet" or "m"

More examples

Runnable scripts in examples/:

	Script
XC	xc_examples.py, compare_improvement.py, standardize_one_result.py
Track	track_outdoor_examples.py, track_indoor_examples.py, track_compare_meets.py
Both	race_context_example.py, load_dataset_example.py

load_dataset_example.py exits with code 1 if Zenodo CSVs are not in data/ — that is expected without the optional dataset.

pip install nrcd
python examples/xc_examples.py
python examples/track_outdoor_examples.py

Install

Requires Python 3.10+.

pip install nrcd              # after first PyPI release
pip install "nrcd[apis]"      # optional: weather / elevation APIs
pip install "nrcd[data]"      # optional: Zenodo CSV helpers (pandas)

Until the package is on PyPI, install from source:

git clone https://github.com/National-Running-Club-Database/nrcd
cd nrcd
pip install -e .

From source (development):

git clone https://github.com/National-Running-Club-Database/nrcd
cd nrcd
pip install -e ".[dev]"
pip install -e ".[dev,apis]"

API keys (optional — nrcd.enrich only)

Standardization does not need API keys. Use enrichment only when backfilling weather or meet altitude from city/state.

1. pip install "nrcd[apis]"
2. → → set NRCD_OPENWEATHER_API_KEY
3. For weather at a race date/time, also → NRCD_TIMEZONE_API_KEY
4. Meet altitude uses free USGS EPQS (no key) after OpenWeather geocodes the city

export NRCD_OPENWEATHER_API_KEY="your_key"
export NRCD_TIMEZONE_API_KEY="your_key"   # weather only
export NRCD_GEOCODE_COUNTRY_SUFFIX=US     # optional; ISO country for geocoding

Live tests (optional): copy local_api_keys.env.example → local_api_keys.env (gitignored), add your OpenWeather key, then pytest -m live_api -v. AQI history starts 2020-11-27; default test date is 2024-10-12.

Full walkthrough: . In Python: from nrcd.enrich import API_GUIDE; print(API_GUIDE).

Historical OpenWeather timemachine weather may require a paid OpenWeather plan; geocoding + USGS altitude often work on the free tier.

Geographic coverage (nrcd.enrich)

Method	Example	Weather	Altitude (USGS)
US city + state	city="Notre Dame", state="IN"	✅	✅ (US)
City + country	city="London", country="GB"	✅	⚠️ set meet_elevation non-US
Free-form query	geocode_query="Paris,FR"	✅	⚠️ same
Config / env default country	EnrichConfig(geocode_country_suffix="CA") or NRCD_GEOCODE_COUNTRY_SUFFIX=CA	✅	⚠️ same
Lat/lon	latitude=51.5, longitude=-0.12	✅ global	⚠️ US-focused EPQS

import datetime as dt
from nrcd.enrich import EnrichConfig, enrich_race_context
from nrcd.standardize import RaceContext

# International weather — city + country (no US state required)
ctx = RaceContext(
    time_str="15:30",
    gender="M",
    sport_name="Cross Country",
    reported_distance="10k",
    city="London",
    country="GB",
    event_date=dt.date(2024, 10, 12),
    event_time=dt.time(11, 0),
)
enrich_race_context(ctx, fetch_altitude=False)  # skip USGS outside US

# Or free-form geocode query
ctx.geocode_query = "Paris,FR"

Standardization has no geographic limit — only optional enrichment does.

Do you need the NRCD dataset?

Use case	Zenodo CSVs needed?
Standardize your own results	No
examples/ scripts	No
nrcd.enrich API backfill	No
examples/load_dataset_example.py only	Yes (optional)

Optional public export: (see ).

API

Full parameter tables: from nrcd import PARAMETERS_DOC or help(nrcd.standardize).

Entry points

Quick start and examples import pipelines from nrcd.standardize. The same standardize_* helpers are also on top-level nrcd; utilities like format_time stay on nrcd.standardize only.

Function	Import from	Use for
standardize_xc	nrcd or .standardize	Cross country — optional target distance (target_distance_m, target_distance + unit, or "8k")
standardize_road	nrcd or .standardize	Road / marathon — event_name; weather, grade, altitude
standardize_outdoor_track	nrcd or .standardize	Outdoor track — event_name; wind on sprints
standardize_indoor_track	nrcd or .standardize	Indoor track — event_name; lap length / banking
standardize_result	nrcd or .standardize	Low-level — any sport_name (advanced)
standardize_seconds	nrcd or .standardize	Dispatch from a RaceContext / XCRaceContext row
standardize_xc_detail	.standardize	XC pipeline with per-step breakdown (StandardizeDetail)
standardize_result_detail	.standardize	Track/road pipeline with breakdown (wind, weather, grade, …)
standardize_seconds_detail	.standardize	Breakdown from a RaceContext row
standardize_dataframe	.standardize	Batch rows → std_time_sec; optional enrich=True (nrcd[data,apis])
enrich_dataframe	.standardize	Batch backfill weather/altitude on rows (cache dedupes per meet)
enrich_race_context	nrcd.enrich	Fill missing weather/altitude on a context (pip install "nrcd[apis]")

nrcd.standardize — pipelines & context

Name	Description
RaceContext	Dataclass for one result (XC or track); time_str or time_sec
XCRaceContext	XC-focused RaceContext subclass
StandardizeDetail	raw_sec, std_sec, and ordered steps from a *_detail call
StandardizeStep	One step: name, factor, delta_sec, time_before_sec, …
row_to_race_context	Build RaceContext from one DataFrame row
resolve_column_map	Map RaceContext fields → DataFrame columns
COLUMN_ALIASES	Default NRCD column aliases (result_time, altitude, …)
StandardizeConfig	Paper coefficients (Riegel exponents, heat k, grade bases, …)
PARAMETERS_DOC	Full required/optional parameter reference (text)
PARAMETER_SPECS	Same metadata as structured ParameterSpec tuples
parameter_specs()	Return PARAMETER_SPECS
`required_for("xc"	"road"

nrcd.standardize — time, distance, units

Name	Description
parse_time	"22:15", "1:10:13", or seconds → float seconds
format_time	Seconds → clock string; returns "" for negative/NaN/inf
parse_distance	"5k", 8, "8000m" + unit → meters
distance_to_meters	Numeric distance with distance_unit (m / km / mi)
c_to_f, f_to_c	Temperature conversion
feet_to_meters, meters_to_feet	Length conversion
temperature_to_fahrenheit	Value + temp_unit (F / C) → °F
venue_elevation_to_feet	Meet altitude + venue_elevation_unit (ft / m) → ft
grade_percent_from_feet	Vertical ft over course → % grade
grade_percent_from_meters	Vertical m over course → % grade
resolve_grade_percent	Normalize gain/loss with grade_input (percent / feet / m)

nrcd.standardize — factors & sport helpers

Name	Description
weather_factor	Heat slowdown multiplier from temp + dew point (°F)
heat_index, heat_slowdown_percent	Hadley-style heat index components
elevation_factor	Maurer grade multiplier from % gain/loss
apply_course_grade_factor	Grade step on a race time
warn_one_sided_course_grade	Warn when only gain or only loss is set
apply_meet_altitude	Peronnet meet-altitude correction
peronnet_f_alt, sea_level_time_seconds	Altitude factor and sea-level equivalent
resolve_meet_altitude_inputs	Parse elevation + barometric pressure from a record
barometric_pressure_hpa_from_record	hPa from row fields
barometric_pressure_torr_from_hpa, parse_barometric_pressure_hpa	Pressure unit helpers
riegel_convert, riegel_exponent	Distance conversion
xc_target_distance_m	Config helper for target distance in meters (8000m M / 6000m F)
apply_factors	Multiply time by weather/grade/altitude/track/wind factors
is_cross_country, is_track, is_outdoor_track, is_indoor_track	Sport name checks
normalize_sport_name, pipeline_kind	Sport string normalization / xc vs track

nrcd.data — Zenodo CSV helpers

Name	Description
meet_altitude_column	Altitude column name in a meet DataFrame
meet_altitude_ft_from_record	Meet altitude (ft) from a merged row + course details
derive_course_details_fields	Derived weather/grade fields from course details

nrcd.enrich — optional APIs (pip install "nrcd[apis]")

Name	Description
API_GUIDE	Full signup guide (text); see also
EnrichConfig	Throttle intervals, cache TTL, API keys
api_keys_from_env	Load keys from environment
fetch_weather	Temperature, dew point, humidity, AQI — global with lat/lon; US city/state by default
lookup_altitude_ft, lookup_altitude_detail, lookup_elevation_ft	Meet altitude (USGS EPQS, ft) — US city/state path; set meet_elevation for non-US
enrich_race_context, enrich_race_context_result	Backfill a RaceContext in place
run_enrich_jobs, EnrichJob, JobResult	Batch enrichment with thread pool
EnrichResult, ApiUsage, WeatherData, AltitudeResult	Result / usage dataclasses
cache_stats, clear_enrich_cache, reset_throttle_state	Cache and rate-limit controls
AQI_HISTORY_AVAILABLE_FROM, AQI_HISTORY_AVAILABLE_UNIX	AQI history window constants

Citation

NRCD: An Open Database of Collegiate Running with Unified Performance Standardization
Jonathan A. Karr Jr, Ryan M. Fryer, Ben Darden, Nicholas Pell, Kayla Ambrose, Evan Hall, Ramzi K. Bualuan, and Nitesh V. Chawla.
Preprint PDF (not yet officially published). arXiv preprint (forthcoming).

Dataset (if using Zenodo export):

Author

Development

pytest

See CONTRIBUTING.md for setup, tests, and pull request guidelines.

See . Package version: (__version__).