https://github.com/bast/coastal-express

Compute nearest neighbor distances along the coast with a view angle.
https://github.com/bast/coastal-express

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Compute nearest neighbor distances along the coast with a view angle.

• Host: GitHub
• URL: https://github.com/bast/coastal-express
• Owner: bast
• License: mpl-2.0
• Created: 2017-01-12T15:18:07.000Z (over 9 years ago)
• Default Branch: main
• Last Pushed: 2023-05-30T14:53:09.000Z (almost 3 years ago)
• Last Synced: 2025-03-01T16:36:57.312Z (about 1 year ago)
• Language: Python
• Homepage:
• Size: 36.1 KB
• Stars: 1
• Watchers: 3
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.rst
  • License: LICENSE

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README

          
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Coastal express

===============

Compute nearest neighbor distances along the coast with a view angle.

Installation

------------

::

  $ pip install cx

Example

-------

::

  cx --boundary="$PWD/boundary.txt" \

     --islands="$PWD/islands.txt" \

     --view-angle=90.0 \

     --min-distance=3.0 \

     --max-distance=40.0 \

     --output-dir="$PWD/output"

Available options

-----------------

::

  $ cx --help

  Usage: cx [OPTIONS]

  Options:

    --boundary TEXT      File containing the boundary.

    --islands TEXT       File(s) containing island data - you can use wildcards.

    --view-angle TEXT    View angle in degrees.

    --min-distance TEXT  Min distance.

    --max-distance TEXT  Max distance.

    --output-dir TEXT    Output folder.

    --help               Show this message and exit.

Definition of the view angle

----------------------------

The code will form view vectors perpendicular to the coastline. The code will

make sure that along the boundary, the vectors point towards "inside" and along

islands they point towards "outside". The view vector is computed to be

perpendicular to the vector connecting the two neighboring points of the

current point.

The view angle of N degrees defines a view sector N/2 degrees to both sides of

the view vector.  In other words a view angle of N degrees is N degrees wide in

total and is oriented symmetrically around the view vector which is

perpendicular to the coast line.

Input and output formats

------------------------

The code will read boundary and island files. It assumes that the first line in

the boundary file contains the total number of polygon points, followed by one

line per point.  First and last polygon point are expected to be the same

point.  Two first numbers in each line are assumed to be x and y coordinates in

arbitrary but consistent units.  Each line can contain more numbers and the

code will not worry about these.

The code can read one or many island files. Each island file can contain one or

many polygons.  Each polygon starts with one line specifying the total number

of points.  First and last polygon point are expected to be the same point.

Each point line is interpreted the same way as the boundary.

The output format preserves all lines and numbers and the only thing it will do

is to append each point line by the computed distance. In other words each

point line will become longer by one number.