Extract body weight from Apple Health Export and save to csv.

convert.py

import xml.etree.ElementTree as ET
import csv
from datetime import datetime

def export_body_mass_to_csv(xml_file, csv_file):
    context = ET.iterparse(xml_file, events=("end",))
    
    with open(csv_file, 'w', newline='', encoding='utf-8') as f:
        writer = csv.writer(f)
        writer.writerow(['Date', 'Weight'])
        count = 0
        
        for event, elem in context:
            if elem.tag == "Record" and elem.get("type") == "HKQuantityTypeIdentifierBodyMass":
                date_str = elem.get("creationDate")
                weight = elem.get("value")
                # Parse the date string and convert it to ISO 8601 format.
                try:
                    dt = datetime.strptime(date_str, "%Y-%m-%d %H:%M:%S %z")
                    formatted_date = dt.isoformat()  # e.g., 2017-09-26T18:30:11+09:00
                except Exception as e:
                    formatted_date = date_str  # Fallback in case of parsing error

                writer.writerow([formatted_date, weight])
                count += 1
                if count % 1000 == 0:
                    print(f"Processed {count} records...")
            elem.clear()
        print(f"Finished processing {count} records.")

if __name__ == '__main__':
    export_body_mass_to_csv('export.xml', 'body_mass.csv')