MobilityDB SQLAlchemy

This package provides extensions to SQLAlchemy for interacting with MobilityDB. The data retrieved from the database is directly mapped to time-indexed pandas DataFrame objects. TGeomPoint and TGeogPoint objects can be optionally mapped to movingpandas' Trajectory data structure.

Thanks to the amazing work by MobilityDB and movingpandas teams, because of which this project exists.

A demo webapp built using this library is now available online:

Live Demo: https://mobilitydb-sqlalchemy-demo.adonmo.com

Source Code: https://github.com/adonmo/mobilitydb-sqlalchemy-demo

Installation

The package is available on PyPI, for Python >= 3.7

pip install mobilitydb-sqlalchemy

Usage

from mobilitydb_sqlalchemy import TGeomPoint

from sqlalchemy import Column, Integer
from sqlalchemy.ext.declarative import declarative_base
Base = declarative_base()

class Trips(Base):
    __tablename__ = "test_table_trips_01"
    car_id = Column(Integer, primary_key=True)
    trip_id = Column(Integer, primary_key=True)
    trip = Column(TGeomPoint)

trips = session.query(Trips).all()

# Querying using MobilityDB functions, for example - valueAtTimestamp
session.query(
    Trips.car_id,
    func.asText(
        func.valueAtTimestamp(Trips.trip, datetime.datetime(2012, 1, 1, 8, 10, 0))
    ),
).all()

There is also a tutorial published on Anita Graser's blog.

For more details, read our documentation (specifically, the quickstart).

Contributing

Issues and pull requests are welcome.

• For proposing new features/improvements or reporting bugs, create an issue.
• Check open issues for viewing existing ideas, verify if it is already proposed/being worked upon.
• When implementing new features make sure to add relavant tests and documentation before sending pull requests.

Setup environment

First, make sure you have poetry installed Then, get the dependencies by running (in the project home directory):

poetry install

Also make sure you setup git hooks locally, this will ensure code is formatted using black before committing any changes to the repository

pre-commit install

Running Tests

Spin up a mobilitydb instance

docker volume create mobilitydb_data
docker run --name "mobilitydb" -d -p 25432:5432 -v mobilitydb_data:/var/lib/postgresql codewit/mobilitydb

Run the tests

movingpandas is an optional dependency - but to run tests you would need it. So if this is your first time running tests, install it by running:

# Currently installing the optional dependency of movingpandas
# using `poetry install -E movingpandas` doesn't work

# To get movingpandas use pip instead of poetry, run the following (in exact order):
poetry shell
pip install cython
pip install git+https://github.com/SciTools/cartopy.git --no-binary cartopy
pip install movingpandas

# This is because of movingpandas dependency cartopy not being PEP 518 compliant
# Refer: https://github.com/SciTools/cartopy/issues/1112

Now, you can actually run the tests using:

poetry run pytest