shapelyM 0.0.4.dev3

Linear referencing for shapley LineStrings

ShapelyM, linear referencing in 3D

The term linear referencing emerged from engineering applications where it was preferable to locate a point along a linear feature (often roads) by referencing that location to some other well-defined location, rather than using classical geographic coordinate systems. The most familiar illustration of linear referencing is the mile markers along U.S. highways (Federal Highway Administration 2001, Federal Transit Administration 2003).

Shapely is a BSD-licensed Python package for manipulation and analysis of planar geometric objects. It is based on the widely deployed GEOS (the engine of PostGIS) and JTS (from which GEOS is ported) libraries. It can be useful to specify position along linear features such as LineStrings and MultiLineStrings with a 1-dimensional referencing system. Shapely supports linear referencing based on length or distance, evaluating the distance along a geometric object to the projection of a given point, or the point at a given distance along the object.

ShapelyM can be used to linear referencing in 3D and is designed to work (without) shapely.

Way of working

1. project (3d) point on on 2d polyline (representation of a 3d polyline)
2. get measure
3. get height on polyline
4. get side of line (by azimuth)

Visual

Usage:

from shapely.geometry import Point
from shapelyM import LineStringMeasure, MeasurePoint

line_measure = LineStringMeasure([[3, 0, 0], [3, 10, 0], [3, 20, 0], [3, 30, 0]])
projection = line_measure.project(Point(0, 5, 0))
# or:
# projection = line_measure.project(MeasurePoint(0, 5, 0))

Returns:

{
    'point': MeasurePoint, 
    'point_on_line': MeasurePoint, 
    'distance_to_line': 5.830951894845301, 
    'distance_to_line_2d': 3.0, 
    'distance_along_line': 7.0710678118654755, 
    'side_of_line': 'Left'
}

MeasurePoint:

{
    'x': 3.0,
    'y': 5.0,
    'z': 5.0,
    'm': 7.0710678118654755,
    'shapely': shapely.geometry.point.Point
}

Contribute

Feel free to do some black math magic, add test or make suggestions.

Roadmap:

• make prototype work

• bumpversion including release type

• pipeline | make : black

• pipeline | make : type checking

• pipeline | deploy on pypi by GH A

• version 0.1.0-alpha

• implement "point on side of line"

• version 0.1.0-beta

• implement LineStringMeasure from shapely Linestring

• return profile line on from and to measures as shapely

• refactor

• version 0.2.0-alpha

• make it work without shapely but easy to use with shapely

• ....

• ....

• 100% test coverage

• version 1.0.0

Requirements

New python project uses pyproject.toml to manage requerments and can be build by a newer build backend. For now we use flit https://flit.pypa.io/en/latest/index.html. Flit also doesn’t help you manage dependencies: you have to add them to pyproject.toml by hand. Tools like Poetry and Pipenv have features which help add and update dependencies on other packages. https://python-poetry.org/

Build and Test

Install MakeFile for quality of life

After setting up a venv we use make install to build a fresh pulled repo

Code quality checks and testing needs to be passed and will be checked on every commit and in the pipeline. If code wont pass it wont commit so make sure to check it before with make check-all!

We use:

• pytest for testing, manual by make test in a console.
• flake8 and black for linting, manual by make lint in a console.
• myPy for typechecking, manual by make typecheck in a console.
• black and isort, manual by make format in a console.
• bumpversion for changing the version
• pyAutocad for debug visualizing

We use flit as a build-backend and for managing (optional) dependencies.

Testing

Make an effort to test each bit of functionality you add. Try to keep it simple.

Links

• make
• flake8
• black
• myPy
• iSort
• flit
• bumpversion