A little function to extract heart rates with absolute timestamps from Polar CSV files

extract_hr_from_polar_csv.py

def extract_hr_from_polar_csv(filename):
    
    # read header and data
    h = pd.read_csv(filename, nrows=2)
    d = pd.read_csv(filename, skiprows=2)
    
    # parse start time
    datetime_string = h["Date"].values[0] + " " + h["Start time"].values[0]
    starttime = datetime.strptime(datetime_string, '%d-%m-%Y %H:%M:%S')
    
    # function for parsing time deltas in data
    def parse_timedelta_simple(string):
        parsed = [int(t) for t in string.split(":")]
        return timedelta(hours=parsed[0], minutes=parsed[1], seconds=parsed[2])
    parse_timedelta = np.vectorize(parse_timedelta_simple)
    
    # calculate absolute time
    d["Absolute time"] = starttime + parse_timedelta(d["Time"])
    
    # return absolute time and hr
    return d["Absolute time"], d["HR (bpm)"]