GlycoSignal

Python library for CGM data analysis — individually callable glycemic metrics, day/sliding-window segmentation, and ML-ready feature matrices.

pip install GlycoSignal

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Quick start

import glycosignal as gs

df = gs.load_csv("cgm.csv")
df = gs.clean_cgm(df)

# Individual metrics
gs.mean_glucose(df)                             # 138.5
gs.time_in_range_percent(df, low=70, high=180)  # 93.1

# Segment → feature matrix  (the standard pipeline)
segs = gs.create_day_segments(df)               # 24 h, midnight anchor
X    = gs.build_feature_map(segs.windows)       # 32 features × n_days

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Input format

Two required columns; everything else is auto-detected (case-insensitive).

Column	Required	Recognized aliases
Timestamp	Yes	time, datetime, date_time, date
Glucose	Yes	Glucose Value (mg/dL), gl, sgv, glucose_mg_dl, bg
subject	Multi-subject only	id, ptid, patient_id, subjectid

# Override auto-detection
df = gs.load_csv("data.csv", timestamp_col="time_utc", glucose_col="bg_mg_dl")

# Multiple subjects — one file with subject column
df = gs.io.load_cgm_file("all.csv", subject_col="ptid")

# Multiple subjects — one CSV per subject in a folder
df = gs.io.load_cgm_folder("data/subjects/")

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Data segmentation

Both functions return WindowResult(windows, metadata). The windows DataFrame flows directly into build_feature_map().

Daily segments

from glycosignal import windows

segs = windows.create_day_segments(df)                    # midnight–midnight (default)
segs = windows.create_day_segments(df, anchor_time="08:00")             # 8 AM–8 AM
segs = windows.create_day_segments(df, anchor_time="08:00",
                                   min_fraction=0.7,      # drop days < 70 % coverage
                                   group_col="subject")   # multi-subject

print(segs.metadata)
# {'n_groups': 1, 'n_valid_windows': 7, 'n_discarded_partial_days': 0, ...}

Sliding windows

result = windows.create_sliding_windows(df, window_hours=6, step_hours=1)
result = windows.create_sliding_windows(df, window_hours=12, step_hours=12,
                                        anchor_time="08:00")
result = windows.create_sliding_windows(df, window_hours=24, overlap_hours=12)
result = windows.create_sliding_windows(df, window_hours=24, step_hours=6,
                                        group_col="subject")

Key parameters: window_hours, step_hours, anchor_time, min_fraction (default 0.0 — keep all windows), group_col, interpolate, max_gap_points.

Output

The windows DataFrame is long-format — one row per (window, time-point):

window_id	subject	date	Timestamp	Glucose
S01_2023-01-02	S01	2023-01-02	2023-01-02 00:00	112.4

Non-midnight anchors append _HHMM to the window ID (e.g. S01_2023-01-02_0800).

Saving as wide-format CSV

wide = windows.pivot_windows_wide(segs.windows)
wide.to_csv("segments.csv", index=False)
# → columns: date | subject | 00:00 | 00:05 | … | 23:55
# For non-midnight anchor (e.g. "08:00"): 08:00 | … | 23:55 | 00:00 | … | 07:55

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Glycemic metrics

Every metric is a standalone function. See the full metric reference for all formulas.

from glycosignal import metrics

# Core
metrics.mean_glucose(df)                              # 138.5
metrics.median_glucose(df)
metrics.std_glucose(df)
metrics.cv(df)                                        # 17.7 %
metrics.time_in_range_percent(df, low=70, high=180)   # 93.1 %
metrics.time_above_range(df, threshold=180)
metrics.time_below_range(df, threshold=70)

# Variability
metrics.mage(df)                                      # 27.0
metrics.j_index(df)
metrics.conga(df)
metrics.modd(df)
metrics.grade(df)

# Risk indices
metrics.lbgi(df)
metrics.hbgi(df)
metrics.adrr(df)
metrics.gri(df)                                       # 7.2

# Grouped helpers — return dicts
metrics.basic_stats(df)          # mean, median, min, max, q1, q3
metrics.variability_metrics(df)  # sd, cv, j_index, mage
metrics.risk_indices(df)         # lbgi, hbgi, adrr, gri
metrics.summary_dict(df)         # all of the above combined

Performance tip — call prepare() once when computing many metrics on the same data:

from glycosignal.schemas import prepare
p = prepare(df)
metrics.mean_glucose(p); metrics.cv(p); metrics.lbgi(p)

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Feature matrices

from glycosignal import windows, features

segs = windows.create_day_segments(df)
X = features.build_feature_map(segs.windows)           # 32 features × n_windows

# Subset
X = features.build_feature_map(segs.windows,
    feature_names=["mean_glucose", "cv", "tir_70_180_pct", "mage", "lbgi"])

# Single window → dict
features.build_feature_vector(window_df, feature_names=["mean_glucose", "cv"])

# List of DataFrames (one per subject)
features.build_feature_table([df_s01, df_s02], record_ids=["S01", "S02"])

Feature registry

gs.list_features()                      # all 32 names
gs.list_features(category="risk")       # ['adrr', 'gri', 'hbgi', 'lbgi']
gs.get_feature_metadata()               # DataFrame: name | description | category
gs.get_feature("gri").description       # 'Glucose Risk Index (Klonoff et al. 2023)'

# Register a custom feature
from glycosignal.registry import DEFAULT_REGISTRY
DEFAULT_REGISTRY.register(name="my_metric", func=my_fn,
                           description="...", category="variability")

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Preprocessing

from glycosignal import preprocessing

df     = preprocessing.clean_cgm(df)                              # drop NaN, sort, enforce positive
report = preprocessing.validate_cgm(df)                           # structured quality report
gaps   = preprocessing.detect_gaps(df)                            # DataFrame of gap intervals
df     = preprocessing.resample_cgm(df, freq="5min")              # regular grid
df     = preprocessing.interpolate_cgm(df, method="pchip",
                                        max_gap_points=12)
df     = preprocessing.convert_units(df, from_unit="mmol/L",
                                      to_unit="mg/dL")

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Event detection

Returns a DataFrame with start_time, end_time, duration_minutes, event_type.

from glycosignal import detect

detect.detect_hypoglycemia(df, threshold=70, min_duration_minutes=15)
detect.detect_hyperglycemia(df, threshold=180, min_duration_minutes=15)
detect.detect_nocturnal_events(df, start_hour=0, end_hour=6)
detect.detect_postprandial_excursions(df, rise_threshold=50)

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Plotting

All functions return (fig, ax) and never call plt.show().

from glycosignal import plotting

fig, ax = plotting.plot_glucose_timeseries(df, subject="P001")
fig, ax = plotting.plot_daily_overlay(df)
fig, ax = plotting.plot_agp(df)
fig, ax = plotting.plot_histogram(df)
fig.savefig("output.png", dpi=150)

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CLI

glycosignal summary data.csv
glycosignal windows data.csv --window-hours 24 --overlap-hours 0 --output windows.csv
glycosignal features windows.csv --output features.csv
glycosignal features windows.csv --features mean_glucose,cv,lbgi,gri
glycosignal list-features
glycosignal list-features --category risk

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License

MIT. Copyright (c) 2024 Jiafeng Song. See LICENSE.