Note

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Project Connections#

In this example, we show how to use AequilibraE’s database connections within a project.

References

See also

Several functions, methods, classes and modules are used in this example:

# Imports
from uuid import uuid4
from tempfile import gettempdir
from pathlib import Path

import geopandas as gpd
import pandas as pd

from aequilibrae.utils.create_example import create_example

# We create the example project inside our temp folder.
fldr = Path(gettempdir()) / uuid4().hex
project = create_example(fldr, "sioux_falls")

All AequilibraE projects presents four types of connections in the form of properties:

  • General connection to the project database

  • Spatial connection to the project database

  • General connection to the results database

  • Spatial connection to the transit database

Each connection can be easily accessed as follows:

with project.db_connection as conn:
    matrices = pd.read_sql("SELECT * FROM matrices", conn)

matrices

We encourage using spatial connections only when handling spatial data.

with project.db_connection_spatial as conn:
    nodes = gpd.read_postgis("SELECT zone_id, ST_AsBinary(geometry) geom FROM zones;", con=conn, geom_col="geom", crs=4326)

nodes.head()

For accessing both results and transit databases, the procedure is the same.

When you’re done, don’t forget to close the project.

project.close()

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