Accessing Project Data#

An AequilibraE project helds geometric information that can be accessed by the user in three different classes: Links, Nodes, and Zoning. In this section, we’ll cover the main points regarding them.

`project.network.links`#

This method allows you to access the API resources to manipulate the ‘links’ table. Each item in the ‘links’ table is a Link object.

>>> from shapely.geometry import LineString

>>> project = create_example(project_path, "coquimbo")

>>> project_links = project.network.links

# Let's add a new field to our 'links' table
>>> project_links.fields.add("my_field", "This is an example", "TEXT")

# To save this modification, we must refresh the table
>>> project_links.refresh_fields()

# Let's add a new link to our project
>>> new_link = project_links.new()
>>> new_link.geometry = LineString([(-71.304754, -29.955233), (-71.304863, -29.954049)])
>>> new_link.modes = "bctw"

# To add a new link, it must be explicitly saved
>>> new_link.save()

# The 'links' table has three fields which cannot be empty (i.e. with `NULL` values):
# `link_id`, `direction`, and `modes`. When we create a node, `new` automatically
# creates a `link_id`, and sets the default value (0) for direction. Thus, the modes
# information should be added, otherwise, it will raise an error.

# To delete one link from the project, you can use one of the following
>>> other_link = project_links.get(21332)
>>> other_link.delete()

# or
>>> project_links.delete(21337)

# The `copy_link` function creates a copy of a specified link
# It is very helpful case you want to split a link.
# You can check out in one of the usage examples.
>>> link_copy = project_links.copy_link(10972)

# Don't forget to save the modifications to the links layer
>>> project_links.save()

# And refresh the links in memory for usage
>>> project_links.refresh()

References

Link layer changes and expected behavior

`project.network.nodes`#

This method allows you to access the API resources to manipulate the ‘nodes’ table. Each item in the ‘nodes’ table is a Node object.

>>> from shapely.geometry import Point

>>> project_nodes = project.network.nodes

# To get one 'Node' object
>>> node = project_nodes.get(10070)

# We can check the existing fields for each node in the 'nodes' table
>>> node.data_fields()
['node_id', 'is_centroid', 'modes', 'link_types', 'geometry', 'osm_id']

# Let's renumber this node and save it
>>> node.renumber(1000)
>>> node.save()

# A node can also be used to add a special generator
# `new_centroid` returns a `Node` object that we can edit
>>> centroid = project_nodes.new_centroid(2000)

# Don't forget to add a geometry to your centroid if it's a new node
# This centroid corresponds to the Port of Coquimbo!
>>> centroid.geometry = Point(-71.32, -29.94)

# As this centroid is not associated with a zone, we must tell AequilibraE the initial area around
# the centroid to look for candidate nodes to which the centroid can connect.
>>> centroid.connect_mode(area=centroid.geometry.buffer(0.01), mode_id="c")

# Don't forget to update these changes to the nodes in memory
>>> project_nodes.refresh()

# And save them into your project
>>> project_nodes.save()

# Last but not less important, you can check your project nodes
# `project_nodes.data` returns a geopandas GeoDataFrame.
>>> nodes_data = project_nodes.data

>>> # or if you want to check the coordinate of each node in the shape of
>>> # a Pandas DataFrame
>>> coords = project_nodes.lonlat
>>> coords.head(3) 
  node_id        lon        lat
0   10037 -71.315117 -29.996804
1   10064 -71.336604 -29.949050
2   10065 -71.336517 -29.949062

References

Node layer changes and expected behavior

`project.zoning`#

This method allows you to access the API resources to manipulate the ‘zones’ table. Each item in the ‘zones’ table is a Zone object.

>>> from shapely.geometry import Polygon

>>> project_zones = project.zoning

# Let's start this example by adding a new field to the 'zones' table
>>> project_zones.fields.add("parking_spots", "Number of public parking spots", "INTEGER")

# We can check if the new field was indeed created
>>> project_zones.fields.all_fields() 
['area', 'employment', 'geometry', 'name', 'parking_spots', 'population', 'zone_id']

# Now let's get a zone and modifiy it
>>> zone = project_zones.get(40)

# By disconnecting the transit mode
>>> zone.disconnect_mode("t")

# Connecting the bicycle mode
>>> zone.connect_mode("b")

# And adding the number of public parking spots in the field we just created
>>> zone.parking_spots = 30

# You can save this changes if you want
>>> zone.save()

# The changes connecting / disconnecting modes reflect in the zone centroids
# and can be seen in the 'nodes' table.

# To return a dictionary with all 'Zone' objects in the model
>>> project_zones.all_zones() 
{1: ..., ..., 133: ...}

# If you want to delete a zone
>>> other_zone = project_zones.get(38)
>>> other_zone.delete()

# Or to add a new one
>>> zone_extent = Polygon([(-71.3325, -29.9473), (-71.3283, -29.9473), (-71.3283, -29.9539), (-71.3325, -29.9539)])

>>> new_zone = project_zones.new(38)
>>> new_zone.geometry = zone_extent

# We can add a centroid to the zone we just created by specifying its location or
# pass `None` to use the geometric center of the zone
>>> new_zone.add_centroid(Point(-71.33, -29.95))

# Let's refresh our fields
>>> project_zones.refresh_geo_index()

# And save the new changes in the project
>>> project_zones.save()

# Finally, to return a geopandas GeoDataFrame with the project zones
>>> zones = project_zones.data

# To get a Shapely Polygon or Multipolygon with the entire zoning coverage
>>> boundaries = project_zones.coverage()

# And to get the nearest zone to a given geometry
>>> project_zones.get_closest_zone(Point(-71.3336, -29.9490))
57

>>> project.close()

Accessing Project Data#

project.network.links#

project.network.nodes#

project.zoning#

`project.network.links`#

`project.network.nodes`#

`project.zoning`#