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Sample: PageRank Algorithm (Python)

python/2_CoreConcepts/pageRank/README.md

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Sample: PageRank Algorithm (Python)

Known issue — version-pinned sample. Unlike the other samples in this repository, this sample is pinned to cuda-core<1.0.0. The reason is that cudf-cu13 transitively requires numba-cuda<0.29.0, and every numba-cuda release in that range pins cuda-core<1.0.0. Installing this sample's requirements.txt into a shared environment will downgrade cuda-core and break the other samples (which use the 1.0 API).

The recommended workflow is one of:

  • Install this sample's requirements in a dedicated virtual environment, or
  • Re-run the other samples' pip install -r requirements.txt afterwards to upgrade cuda-core back to 1.0.

This sample will be re-aligned with the rest of the repository (cuda-core>=1.0.0) once cudf-cu13 ships a release that lifts its numba-cuda upper bound.

Description

Demonstrates GPU-accelerated PageRank computation for graph analysis using RAPIDS cuGraph, with cuda.core for device, stream, and GPU timing. This sample focuses on cuda.core integration with high-level libraries (cuGraph/cuDF); for custom kernel programming (Program, LaunchConfig, launch), see the blockwiseSum sample.

What You'll Learn

  • Graph representation using cuDF DataFrames for edge lists
  • GPU-optimized PageRank via RAPIDS cuGraph library
  • Performance comparison between cuGraph GPU and CPU reference implementation
  • cuda.core device/stream management and GPU timing

Key Libraries

  • cugraph - RAPIDS GPU-accelerated graph analytics
  • cudf - RAPIDS GPU DataFrame library
  • cuda.core - Device, stream, and event APIs for GPU timing
  • cupy - GPU array library (Stream.from_external for cuDF/cuGraph)
  • numpy - CPU reference implementation

Key APIs

From cuda.core:

  • Device(0) - Create device, device.set_current(), device.create_stream()
  • EventOptions(enable_timing=True) - GPU timing via stream.record()
  • cp.cuda.Stream.from_external(stream).use() - Make cuDF/cuGraph use cuda.core stream

From cuGraph:

  • cugraph.Graph(directed=True) - Create directed graph structure
  • Graph.from_cudf_edgelist() - Build graph from edge list DataFrame
  • cugraph.pagerank() - GPU-accelerated PageRank algorithm

From cuDF:

  • cudf.DataFrame() - GPU DataFrame for edge lists

Requirements

Hardware:

  • NVIDIA GPU with Compute Capability 7.0 or higher
  • Minimum GPU memory: 512 MB (for 10K node graph)

Software:

  • CUDA Toolkit 13.0 or newer
  • Python 3.10 or newer
  • See requirements.txt for package dependencies

Platform Support:

This sample depends on RAPIDS (cugraph-cu13, cudf-cu13, dask-cuda), which is currently published only as Linux (manylinux) wheels on pypi.nvidia.com — no Windows wheels exist. On Windows the sample exits early with a waive message and exit code 2 instead of attempting an install that cannot succeed.

Installation

bash
cd /path/to/cuda-samples/python/2_CoreConcepts/pageRank
python3 -m venv venv
source venv/bin/activate
pip install -r requirements.txt

How to Run

bash
python pageRank.py

Algorithm

The PageRank formula iteratively computes node importance:

PR(v) = (1-d)/N + d * Σ PR(u)/out_degree(u)

Where:

  • d = damping factor (typically 0.85)
  • N = total number of nodes
  • Sum is over all nodes u that link to v

Expected Output

============================================================
PageRank Algorithm (using RAPIDS cuGraph)
============================================================

Device: NVIDIA GeForce RTX ...
Compute Capability: sm_XX

Graph Parameters:
  Nodes: 10,000
  Avg edges/node: 15
  Total edges: ~150,000
  Avg in-degree: 14.9

------------------------------------------------------------
GPU PageRank (RAPIDS cuGraph)
------------------------------------------------------------
Time: X.XXX ms

Top 5 nodes by PageRank:
  1. Node XXXXX: 0.XXXXXX
  ...

------------------------------------------------------------
CPU PageRank (Reference)
------------------------------------------------------------
Time: XXXX.XXX ms
Iterations: XX

------------------------------------------------------------
PERFORMANCE SUMMARY
------------------------------------------------------------
GPU (cuGraph): X.XXX ms
CPU (Reference): XXXX.XXX ms
Speedup: XXXX.Xx

------------------------------------------------------------
VERIFICATION
------------------------------------------------------------
GPU vs CPU PageRank scores: Test PASSED

PageRank Properties:
  Sum of scores: 1.000000 (should be ~1.0)
  Sum check: ✓

Done

Files

  • pageRank.py - Python implementation using RAPIDS cuGraph
  • README.md - This file
  • requirements.txt - Sample dependencies

Why cuGraph?

RAPIDS cuGraph provides production-grade, GPU-accelerated graph analytics:

  • Highly optimized - Uses advanced GPU parallelization techniques
  • Scalable - Handles graphs with billions of edges
  • Easy to use - Simple Python API similar to NetworkX
  • Integrated - Works seamlessly with cuDF, cuML, and other RAPIDS libraries

Applications

  • Web page ranking (original Google PageRank)
  • Social network influence analysis
  • Citation network analysis
  • Recommendation systems
  • Fraud detection in financial networks

See Also