Support for Python 3.8

[Zero3]

Hi :)

This project looks pretty cool, and I would like to play around with it. However, I am unable to install it because it requires Python 3.9. I am currently running Windows 7, and the last version of Python to support Windows 7 is Python 3.8. So I wonder whether the requirement for Python 3.9 is necessary? Would it be easy to add support for Python 3.8?

[enzet]

Hello!

Thank you for your interest! I think the best way is to create a separate branch and backport to Python 3.8. Seems to be easy, I just have to do it carefully. I've created an issue to that end: #88.

Honestly, I have very little experience with Windows, and I'm not sure the project is completely cross-platform. Your feedback would be very helpful.

[enzet]

I've backported to Python 3.8. Please, take a look at the branch python3.8. But I'm still not sure whether it works well on Windows.

[Zero3]

Nice. I can actually render the simple test map now :). I will let you know if I run into any more issues.

[Zero3]

Next problem, when calling map-machine render -b 10.3394828,55.3824880,10.4280850,55.4244765:

Traceback (most recent call last):
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\Scripts\map-machine-script.py", line 33, in <module>
    sys.exit(load_entry_point('map-machine==0.1.3', 'console_scripts', 'map-machine')())
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\main.py", line 32, in main
    mapper.ui(arguments)
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\mapper.py", line 254, in ui
    osm_data.parse_osm_file(input_file_name)
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\osm_reader.py", line 396, in parse_osm_file
    self.parse_osm(ElementTree.parse(file_name).getroot())
  File "c:\program files\python38\lib\xml\etree\ElementTree.py", line 1202, in parse
    tree.parse(source, parser)
  File "c:\program files\python38\lib\xml\etree\ElementTree.py", line 595, in parse
    self._root = parser._parse_whole(source)
xml.etree.ElementTree.ParseError: syntax error: line 1, column 0

[enzet]

Finally something works! 🎉 🎉 🎉

The problem is, without input file provided Map Machine downloads OSM data through API and gets You requested too many nodes (limit is 50000). Either request a smaller area, or use planet.osm if the area contains too many elements. I've added error handling for this response. Please, remove the cache file cache/10.339,55.382,10.429,55.425.osm after the update.

Possible solutions:

• try to request a smaller area (obviously :),
• request data through overpass turbo.

I'm planning to support data extracting from a database, but for now, it's not a high priority since it requires a lot of free memory and adds more dependencies.

[Zero3]

Ahh. It works with a smaller region, yeah. Thanks.

What do you mean with regard to overpass turbo? Are you saying that they have an OSM API with less restrictions that one can switch to? I am not familiar with it. Or do you mean making a query in their UI and saving the results to a file and use that with map-machine?

[enzet]

Yes, I mean the second one, making a query and using the JSON results as an input file. I know, this sounds silly, but here's the point. The only way to display a map with a large number of nodes at once on one picture is to filter out some less significant data. However, the main goal of Map Machine is to try to show as many map features as possible. That's why I think the OSM API limitation of 50 K nodes is useful.

Working with the planet.osm, databases, and creating a tile server with all possible tiles is a bit different task and I'm planning to do that in the future.

[Zero3]

Hi again @enzet

Seems like the python3.8 branch is not being kept up to date with main. Any chance of an update, or a merge with main? :)

[enzet]

Hello @Zero3!

Yes, I'll merge main into python3.8. Thanks for reminding me of that.

[Zero3]

Found the problem. The git URL in the installation command in README.md is not correct for the python3.8 branch. The command should probably be like this instead, to get the code from the right branch:

pip install git+https://github.com/enzet/map-machine@python3.8

[Zero3]

Hmm. That command executes, but the files are not updated. I also tried:

pip install --upgrade git+https://github.com/enzet/map-machine@python3.8

But that had no effect either. Probably because the version number has not been increased from 0.1.3 in the source. So it seems like pip install is not a good way to update map-machine. To get the new version, I had to first uninstall the current one:

pip uninstall map-machine

And then run the updated install command, which seems to do the trick.

[Zero3]

Next issue:

  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\Scripts\map-machine-script.py", line 33, in <module>
    sys.exit(load_entry_point('map-machine==0.1.3', 'console_scripts', 'map-machine')())
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\main.py", line 32, in main
    mapper.render_map(arguments)
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\mapper.py", line 311, in render_map
    constructor.construct()
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\constructor.py", line 205, in construct
    self.construct_ways()
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\constructor.py", line 214, in construct_ways
    self.construct_line(way, [], [way.nodes])
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\constructor.py", line 273, in construct_line
    road: Road = Road(
  File "C:\Users\Zero3\AppData\Roaming\Python\Python38\site-packages\map_machine\feature\road.py", line 455, in __init__
    self.placement_offset += self.lanes[lane_number].get_width(
IndexError: list index out of range

[Zero3]

Seems to be a mapping issue that is not handled gracefully by map-machine. I added a comment about it here: #83 (comment)

[enzet]

Hi!

The git URL in the installation command in README.md is not correct for the python3.8 branch.

Sorry, my bad, forgot to update the readme for the branch.

the version number has not been increased from 0.1.3 in the source

Ah, yeah, I'm totally ruining the idea of versioning. I'll update the version.

I added a comment about it here: #83 (comment)

Thank you! I will add a separate issue.