.. DO NOT EDIT.
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.. TO MAKE CHANGES, EDIT THE SOURCE PYTHON FILE:
.. "_auto_examples/creating_models/plot_create_zoning.py"
.. LINE NUMBERS ARE GIVEN BELOW.

.. only:: html

    .. note::
        :class: sphx-glr-download-link-note

        :ref:`Go to the end <sphx_glr_download__auto_examples_creating_models_plot_create_zoning.py>`
        to download the full example code

.. rst-class:: sphx-glr-example-title

.. _sphx_glr__auto_examples_creating_models_plot_create_zoning.py:


.. _create_zones:

Creating a zone system based on Hex Bins
========================================

In this example, we show how to create hex bin zones covering an arbitrary area.

We use the Nauru example to create roughly 100 zones covering the whole modeling
area as delimited by the entire network

You are obviously welcome to create whatever zone system you would like, as long as
you have the geometries for them. In that case, you can just skip the hex bin computation
part of this notebook.

We also add centroid connectors to our network to make it a pretty complete example

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Imports

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.. code-block:: Python

    from uuid import uuid4
    from tempfile import gettempdir
    from os.path import join
    from math import sqrt
    from shapely.geometry import Point
    import shapely.wkb
    from aequilibrae.utils.create_example import create_example, list_examples








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We create an empty project on an arbitrary folder

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.. code-block:: Python

    fldr = join(gettempdir(), uuid4().hex)

    # We can print the list of examples that ship with AequilibraE
    print(list_examples())

    # Let's use the Nauru example project for display
    project = create_example(fldr, "nauru")





.. rst-class:: sphx-glr-script-out

 .. code-block:: none

    ['coquimbo', 'sioux_falls', 'nauru']




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We said we wanted 100 zones

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.. code-block:: Python

    zones = 100








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Hex Bins using Spatialite
-------------------------

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Spatialite requires a few things to compute hex bins.
One of them is the area you want to cover.

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.. code-block:: Python

    network = project.network

    # So we use the convenient network method ``convex_hull()`` (it may take some time for very large networks)
    geo = network.convex_hull()








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The second thing is the side of the hex bin, which we can compute from its area.
The approximate area of the desired hex bin is

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.. code-block:: Python

    zone_area = geo.area / zones
    # Since the area of the hexagon is **3 * sqrt(3) * side^2 / 2**
    # is side is equal to  **sqrt(2 * sqrt(3) * A/9)**
    zone_side = sqrt(2 * sqrt(3) * zone_area / 9)








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Now we can run an SQL query to compute the hexagonal grid.
There are many ways to create hex bins (including with a GUI on QGIS), but we find that
using SpatiaLite is a pretty neat solution.
For which we will use the entire network bounding box to make sure we cover everything

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.. code-block:: Python

    extent = network.extent()

    curr = project.conn.cursor()
    b = extent.bounds
    curr.execute(
        "select st_asbinary(HexagonalGrid(GeomFromWKB(?), ?, 0, GeomFromWKB(?)))",
        [extent.wkb, zone_side, Point(b[2], b[3]).wkb],
    )
    grid = curr.fetchone()[0]
    grid = shapely.wkb.loads(grid)








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Since we used the bounding box, we have WAY more zones than we wanted, so we clean them
by only keeping those that intersect the network convex hull.

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.. code-block:: Python

    grid = [p for p in grid.geoms if p.intersects(geo)]

    # Let's re-number all nodes with IDs smaller than 300 to something bigger as to free space to our centroids to go from 1
    # to N
    nodes = network.nodes
    for i in range(1, 301):
        nd = nodes.get(i)
        nd.renumber(i + 1300)








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Now we can add them to the model
And add centroids to them while we are at it

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.. code-block:: Python

    zoning = project.zoning
    for i, zone_geo in enumerate(grid):
        zone = zoning.new(i + 1)
        zone.geometry = zone_geo
        zone.save()
        # None means that the centroid will be added in the geometric point of the zone
        # But we could provide a Shapely point as an alternative
        zone.add_centroid(None)









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Centroid connectors
-------------------

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.. code-block:: Python

    for zone_id, zone in zoning.all_zones().items():
        # We will connect for walk, with 1 connector per zone
        zone.connect_mode(mode_id="w", connectors=1)

        # And for cars, for cars with 2 connectors per zone
        # We also specify the link types we accept to connect to (can be used to avoid connection to ramps or freeways)
        zone.connect_mode(mode_id="c", link_types="ytrusP", connectors=2)

        # This takes a few minutes to compute, so we will break after processing the first 10 zones
        if zone_id >= 10:
            break








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Let's add special generator zones
We also add a centroid at the airport terminal

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.. code-block:: Python

    nodes = project.network.nodes

    # Let's use some silly number for its ID, like 10,000, just so we can easily differentiate it
    airport = nodes.new_centroid(10000)
    airport.geometry = Point(166.91749582, -0.54472590)
    airport.save()

    # When connecting a centroid not associated with a zone, we need to tell AequilibraE what is the initial area around
    # the centroid that needs to be considered when looking for candidate nodes.
    # Distance here is in degrees, so 0.01 is equivalent to roughly 1.1km
    airport.connect_mode(airport.geometry.buffer(0.01), mode_id="c", link_types="ytrusP", connectors=1)








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.. code-block:: Python

    project.close()








.. rst-class:: sphx-glr-timing

   **Total running time of the script:** (0 minutes 4.368 seconds)


.. _sphx_glr_download__auto_examples_creating_models_plot_create_zoning.py:

.. only:: html

  .. container:: sphx-glr-footer sphx-glr-footer-example

    .. container:: sphx-glr-download sphx-glr-download-jupyter

      :download:`Download Jupyter notebook: plot_create_zoning.ipynb <plot_create_zoning.ipynb>`

    .. container:: sphx-glr-download sphx-glr-download-python

      :download:`Download Python source code: plot_create_zoning.py <plot_create_zoning.py>`


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