Plot heart rate statistics per day from exported Garmin data.

heartrate_stats.py

"""
Plot heart rate statistics per day from exported Garmin data.
"""
import glob
import time
import matplotlib.pyplot as plt
import numpy as np
import pandas as pd
import seaborn as sns
from fitparse import FitFile

timestamps = []
heartrates = []

for filename in list(glob.glob("*_WELLNESS.fit")):
    fitfile = FitFile(filename)
    msgs = list(fitfile.get_messages("monitoring"))

    last_full_timestamp = None
    for msg in msgs:
        timestamp = msg.get_value("timestamp")
        hr = msg.get_value("heart_rate")
        if timestamp is not None:
            timestamp = int(time.mktime(timestamp.timetuple()))
            last_full_timestamp = timestamp
        elif hr is not None and hr > 0:
            assert last_full_timestamp is not None
            timestamp_16 = msg.get_value("timestamp_16")
            # https://www.thisisant.com/forum/viewthread/6374
            timestamp = last_full_timestamp + ((timestamp_16 - (last_full_timestamp & 0xFFFF)) & 0xFFFF)
            timestamps.append(timestamp)
            heartrates.append(hr)

timestamps = np.asarray(timestamps, dtype=float)
heartrates = np.asarray(heartrates)
indices = np.argsort(timestamps)
timestamps = timestamps[indices]
heartrates = heartrates[indices]


df = pd.DataFrame({"timestamps": timestamps,
                   "heartrates": heartrates})
df["timestamps"] = pd.to_datetime(df["timestamps"], unit="s")
df.timestamps.dt.tz_localize("UTC").dt.tz_convert("Europe/Berlin")
df["day"] = df.timestamps.dt.floor("d")

sns.set_theme(style="ticks", palette="pastel")
sns.boxplot(x="day", y="heartrates", data=df)
sns.despine(offset=5, trim=True)
x_dates = df["day"].dt.strftime('%Y-%m-%d').sort_values().unique()
plt.gca().set_xticklabels(labels=x_dates, rotation=45, ha='right')
plt.tight_layout()
plt.show()