geojac 0.2.2

Simplificacion de grafos urbanos y analisis de criminalidad

ACJ: Urban Graph Acceleration & Simplification Framework

ACJ is a high-performance hybrid C++/Python framework for the semantic and topological simplification of large-scale urban street networks. It safely decouples topology from semantic metadata (speed limits, road names, etc.) so that both survive massive graph reductions powered by a CGAL-accelerated C++ core.

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Installation

ACJ is published on PyPI and ships with pre-compiled wheels for Linux, macOS (Apple Silicon & Intel), and Windows. No C++ compilation required.

pip install geojac

For GPU-accelerated real-time visualization, install the optional extras:

pip install "geojac[viz]"

We recommend working inside a virtual environment: python -m venv venv && source venv/bin/activate

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Quick Start — End-to-End Pipeline

import osmnx as ox
from geojac import UrbanNetwork, ACJTopologicalEvaluator
from geojac import CompressionRatioMetric, SemanticSpeedDistortionMetric

# 1. Fetch a raw street network
G = ox.graph_from_place("Barranco, Lima, Peru", network_type="drive")

# 2. Parse into the ACJ registry
network = UrbanNetwork.from_networkx(G)
print(network)
# <UrbanNetwork | Nodes: 312 (Meta: True) | Edges: 847 (Meta: True)>

# 3. Configure metrics and run the evaluator
metrics = [CompressionRatioMetric(), SemanticSpeedDistortionMetric()]
evaluator = ACJTopologicalEvaluator(network, metrics)
results = evaluator.evaluate()

print(results)
print(evaluator.simplified_network)

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API Reference

UrbanNetwork — Core Data Container

The central data structure. Stores topology in Pandas DataFrames and semantic attributes in dictionaries, keeping them decoupled for safe C++ operations.

from geojac import UrbanNetwork

# From an OSMnx / NetworkX graph
network = UrbanNetwork.from_networkx(G)

# From raw DataFrames
# nodes_df must have columns: node_id, x, y  (+ any metadata columns)
# edges_df must have columns: segment_id, node_start, node_end  (+ any metadata columns)
network = UrbanNetwork.from_dataframe(nodes_df, edges_df)

Key attributes:

Attribute	Type	Description
nodes_df	pd.DataFrame	Node topology: node_id, x, y
edges_df	pd.DataFrame	Edge topology: segment_id, node_start, node_end
node_metadata	dict	Per-node semantic attributes keyed by node_id
edge_metadata	dict	Per-edge semantic attributes keyed by segment_id

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MapIndex — Spatial Queries

CGAL-backed spatial index for fast nearest-neighbor point-to-graph assignment. Useful for correlating events (e.g., crime incidents) with street segments or intersections.

from geojac import MapIndex, load_graph
import pandas as pd

graph_data = load_graph(nodes_df, edges_df)
index = MapIndex(graph_data)

# Assign point events to the nearest node
points = pd.DataFrame({'point_id': [1, 2], 'x': [-77.02, -77.03], 'y': [-12.15, -12.14]})
node_assignments = index.assign_to_endpoints(points)
# Returns original DataFrame + 'assigned_node_id' and 'distance' columns

# Assign point events to the nearest edge segment
segment_assignments = index.assign_to_segments(points)
# Returns original DataFrame + 'assigned_segment_id' and 'distance' columns

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ACJTopologicalEvaluator — Simplification Lifecycle

Automates the full pipeline: injects the network into the C++ core, receives the simplified topology with lineage maps, runs semantic resolution, and applies metrics.

from geojac import ACJTopologicalEvaluator, CompressionRatioMetric, SemanticSpeedDistortionMetric

evaluator = ACJTopologicalEvaluator(network, metrics=[
    CompressionRatioMetric(),
    SemanticSpeedDistortionMetric(),
])
results = evaluator.evaluate()

simplified = evaluator.simplified_network  # UrbanNetwork

Built-in metrics:

Class	Measures
CompressionRatioMetric	Node/edge reduction ratio after simplification
SemanticSpeedDistortionMetric	Speed-limit distribution distortion introduced by edge merging

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Visualization (optional viz extra)

GPU-accelerated interactive tools built on VisPy/OpenGL. Requires pip install "geojac[viz]".

from geojac import MapIndex, load_graph
from geojac import render_graph, render_heatmap, render_comparison

graph_data = load_graph(nodes_df, edges_df)
index = MapIndex(graph_data)

# Render the raw street network
render_graph(index)

# Render a heatmap of point assignments over the network
render_heatmap(index, assignments=node_assignments)

# Side-by-side comparison of two networks (e.g., original vs. simplified)
render_comparison(
    index_original, index_simplified,
    title_left="Original", title_right="Simplified"
)

Interactive controls (all render functions):

Key	Action
N	Toggle node layer
L	Toggle segment layer
G	Toggle grid
R	Reset camera view
Q / Esc	Close window

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load_graph / load_map — Data IO

from geojac import load_graph, load_map

# Build a GraphData object from DataFrames (required input for MapIndex)
graph_data = load_graph(nodes_df, edges_df)

# Load from a file path (GeoJSON, Shapefile, etc.)
graph_data = load_map("path/to/network.geojson")

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Developer Installation (From Source)

Required: CMake ≥ 3.15, C++17, CGAL, Boost, pybind11.

# Ubuntu/Debian
sudo apt-get install cmake libcgal-dev libboost-all-dev

# Arch Linux
sudo pacman -S cmake cgal boost pybind11

git clone https://github.com/CdeCasurpie/CS5351-acj.git
cd CS5351-acj
python -m venv venv && source venv/bin/activate
pip install -U pip setuptools wheel
pip install -e .

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Academic Team & Acknowledgements

This framework was developed as part of a thesis research project at the Universidad de Ingeniería y Tecnología (UTEC).

Lead Researchers & Engineers:

• Alejandro Calizaya
• Cesar Perales
• Jerimy Sandoval

Thesis Advisors:

• Eric Javier Biagioli - Academic Director, Department of Computer and Data Science, UTEC (ORCID: 0009-0000-2027-0647)
• Germain García Zanabria - Researcher, Artificial Intelligence Research Group (GINIA), UTEC (ORCID: 0000-0003-3266-9043)