pytrack gps decoder

gpsdecoder.py

class GPSDecoder:
    def __init__(self, i2c=None):
        if i2c is None:
            from machine import I2C
            i2c = I2C(0, mode=I2C.MASTER, pins=('G9', 'G8'))
        self.i2c = i2c
        self.buf = ""
        self.clear()
    def clear(self):
        self.fixStatus = self.lat = self.lng = self.utcTime = None
        self.pdop = self.hdop = self.vdop = None
        self.alt = self.geoid = None
        self.cogT = self.cogM = self.speedKnots = self.speedKm = None
        self.utcDate = None
    def to_decimal(self, pos, mod):
        import math

        dotoffset = pos.find('.')

        if 4 == dotoffset:
            d, m = (pos[0:2], pos[2:])
        elif 5 == dotoffset:
            d, m = (pos[0:3], pos[3:])

        d = float(d)
        m = float(m)

        r = m / 60.0

        result = (d + r)

        if -1 != "SW".rfind(mod):
            result *= -1.0

        return result
    def hasPosition(self):
        result = None != self.fixStatus

        result &= None != self.lat
        result &= None != self.lng
        result &= None != self.utcTime
        result &= None != self.pdop
        result &= None != self.hdop
        result &= None != self.vdop
        result &= None != self.alt
        result &= None != self.geoid
        result &= None != self.fixStatus
        result &= None != self.utcDate
        #result &= None != self.cogT
        #result &= None != self.cogM
        #result &= None != self.speedKnots
        #result &= None != self.speedKm

        return result
    def parse(self):
        from utime import sleep_ms
        from math import modf

        received = self.i2c.readfrom(0x10, 255)

        self.buf += received.decode("utf8")
        lines = self.buf.split("\n")
        off = 0
        for line in lines:
            # if len(line) > 2:
            #     print("line trailer: %s" % hexlify(line[-2:]))
            off += len(line) + 2

            exclude = False
            if not line:
                exclude = True
            elif len(line) <= 1:
                exclude = True
            elif '$' != line[0]:
                exclude = True
            elif line[-1:] != "\r":
                exclude = True

            if exclude:
                self.buf = self.buf[off:]
                continue

            if len(self.buf) > 1024:
                self.buf = self.buf[1+self.buf.rfind("\n"):]

            line = line.strip()

            lastAsterisk = line.rfind('*')

            if -1 != lastAsterisk:
                line = line[:lastAsterisk]

            args = line.split(",")

            command = args[0]

            if command[-3:] == "GLL":
                lat = args[1]
                ns = args[2]
                lng = args[3]
                ew = args[4]
                utcTime = args[5]
                dataValid = args[6]
                positioningMode = args[7]

                self.lat = self.to_decimal(lat, ns)

                self.lng = self.to_decimal(lng, ew)

                self.utcTime = utcTime
            elif command[-3:] == "GSA":
                self.fixStatus = args[2]

                self.pdop = float(args[-3])
                self.hdop = float(args[-2])
                self.vdop = float(args[-1])
            elif command[-3:] == "GSV":
                # Ignored. Pura Groselha.
                pass
            elif command[-3:] == "GGA":
                self.utcTime = args[1]
                self.lat = self.to_decimal(args[2], args[3])

                self.lng = self.to_decimal(args[4], args[5])

                self.fixStatus = args[6]

                self.hdop = float(args[8])
                self.alt = float(args[9])
                self.geoid = float(args[11])
            elif command[-3:] == "VTG":
                #print("args:%s" % repr(args))
                if 0 != len(args[1]):
                    self.cogT = float(args[1])

                if 0 != len(args[3]):
                    self.cogM = float(args[3])

                self.speedKnots = float(args[5])
                self.speedKm = float(args[7])
                self.fixStatus = args[9][0]
            elif command[-3:] == "RMC":
                valid = args[2]

                if "A" == valid:
                    self.utcTime = args[1]
                    self.lat = self.to_decimal(args[3], args[4])
                    self.lng = self.to_decimal(args[5], args[6])
                    self.speedKnots = float(args[7])
                    self.cogM = float(args[8])
                    self.utcDate = args[9]
                    self.fixStatus = args[12][0]
            else:
                print("Not parsed: %s" % repr(args))

            self.buf = self.buf[off:]
        # TODO: Use just the time difference instead of a fixed value
        sleep_ms(500)

        return self.hasPosition()

d = GPSDecoder()

while not d.parse():
    pass

Hello, I don't really undrestand this code. I need to do a tracker do you think this will help me ?

Good Day all,
I'm a very beginner with Pytrak & Python and do not have understood the way to call the constructor & class from gpsdecoder.py.
Would it be possible for one of you to help me by providing an example of main.py calling the class.
My intention is to collect the GGA (NMEA) sentences, including GPS & Altitude.
Thanks in advance for your help.
Best regards.