Grok converts FIT file to KMZ file
Grok converts FIT file to KMZ file
Grok prompt
Grok prompt
We wrote a successful function to decode Garmin FIT files into Mathematica using the Python package garmin_fit_sdk.
In[]:=
decodeFIT[filepath_String]:=Module[{pyStr1,pyStr2},pyStr1="from garmin_fit_sdk import Decoder, StreamfilePath = r\"";pyStr2="\"stream = Stream.from_file(filePath)decoder = Decoder(stream)header = decoder.read_file_header(reset=True)messages, errors = decoder.read()(header, messages, errors)";ExternalEvaluate["Python",pyStr1<>filepath<>pyStr2]];
The first step in a new function is to create a KML file as text to Mathematica which can be used in Google Earth to show a path in red color without the points. From earlier attempts we have learned that altitude is not needed in the kml. The correct option for AltitudeMode is clampToGround, not clamptoground. I have installed the Python package, simplekml. We do not need to read the header file in the above example and the position_lat and position_long are located in record_mesgs.
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Out[]=
garmin-fit-sdk21.178.0,pip25.2,pyzmq27.1.0,simplekml1.3.6
Grok output
Grok output
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createKML[filepath_String]:=Module[{pyStr1,pyStr2,result,kmlText},pyStr1="from garmin_fit_sdk import Decoder, Streamimport simplekmlfilePath = r\"";pyStr2="\"stream = Stream.from_file(filePath)decoder = Decoder(stream)messages, errors = decoder.read()coords = [(msg['position_long'] / 11930464.477, msg['position_lat'] / 11930464.477) for msg in messages['record_mesgs'] if 'position_long' in msg and 'position_lat' in msg]kml = simplekml.Kml()lin = kml.newlinestring(name='Path')lin.coords = coordslin.style.linestyle.color = simplekml.Color.redlin.style.linestyle.width = 4kml.kml()";result=ExternalEvaluate["Python",pyStr1<>filepath<>pyStr2];kmlText=result];
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fname="C:\\Mathematica 14\\Garmin\\Activity\\2025-10-21-07-52-54.fit";
This kml file worked in Google Earth.
kml=createKML[fname];
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Export["C:\\Mathematica 14\\Garmin\\Activity\\2025-10-21-07-52-54.kml",kml,"Text"]
Out[]=
C:\Mathematica 14\Garmin\Activity\2025-10-21-07-52-54.kml
I next asked for Python code to output a KMZ file to the same directory as the input file. KMZ is a zipped KML. The code worked perfectly.
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createKMZ[filepath_String]:=Module[{pyStr1,pyStr2,result},pyStr1="from garmin_fit_sdk import Decoder, Streamimport simplekmlimport zipfileimport osfilePath = r\"";pyStr2="\"stream = Stream.from_file(filePath)decoder = Decoder(stream)messages, errors = decoder.read()coords = [(msg['position_long'] / 11930464.477, msg['position_lat'] / 11930464.477) for msg in messages['record_mesgs'] if 'position_long' in msg and 'position_lat' in msg]kml = simplekml.Kml()lin = kml.newlinestring(name='Path')lin.coords = coordslin.style.linestyle.color = simplekml.Color.redlin.style.linestyle.width = 4kml_text = kml.kml()# Get directory and base name of input filedirectory = os.path.dirname(filePath)base_name = os.path.splitext(os.path.basename(filePath))[0]kml_file = os.path.join(directory, 'doc.kml')kmz_file = os.path.join(directory, base_name + '.kmz')# Save KML text to a temporary filewith open(kml_file, 'w', encoding='utf-8') as f: f.write(kml_text)# Create KMZ by zipping the KML filewith zipfile.ZipFile(kmz_file, 'w', zipfile.ZIP_DEFLATED) as zf: zf.write(kml_file, 'doc.kml')# Delete temporary KML fileos.remove(kml_file)# Return the path to the KMZ filekmz_file";result=ExternalEvaluate["Python",pyStr1<>filepath<>pyStr2]];
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createKMZ[fname]
Out[]=
C:\Mathematica 14\Garmin\Activity\2025-10-21-07-52-54.kmz
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There is a learning curve to getting AIs to program in Python. The trick is to start over quickly after a couple of failed tries. On the first try I wasted about two hours. The second try took ten minutes. If you do not know Python, there is no need to learn it!