retworkx

0.17.1 verified Mon Apr 27 auth: no python

A high-performance graph library for Python, written in Rust, providing directed and undirected graph data structures with efficient algorithms. Current version 0.17.1, release cadence irregular.

pip install retworkx

Common errors

error ModuleNotFoundError: No module named 'retworkx' ↓

cause retworkx not installed or environment not activated

fix

Run pip install retworkx in the correct environment (Python >=3.9).

error TypeError: add_child() missing 1 required positional argument: 'obj' ↓

cause Missing the edge weight argument in add_child

fix

Provide a third argument, e.g., dag.add_child(parent, child, None).

error AttributeError: module 'retworkx' has no attribute 'digraph' ↓

cause Using the deprecated function name from old versions (<0.14.0)

fix

Use retworkx.PyDiGraph() instead of retworkx.digraph().

Warnings

breaking Version 0.14.0 replaced the original function-based API with the class-based API (PyGraph, PyDiGraph). Code using `from retworkx import *` or older function names will break. ↓

fix Migrate to using PyGraph and PyDiGraph classes. See migration guide at https://qiskit.org/documentation/retworkx/

deprecated The `digraph` and `graph` constructor functions are deprecated and removed in 0.14.0. ↓

fix Replace `retworkx.digraph()` with `retworkx.PyDiGraph()` and similarly for undirected graphs.

gotcha Node indices are integers returned by add_node/add_child; do not rely on them being sequential or stable after deletions. ↓

fix Assign custom node data or use node indices immediately; do not assume order.

gotcha Edge weights are optional but must be passed as the third argument to add_child; passing None is acceptable but can lead to type confusion. ↓

fix Always provide an explicit weight (or None) to avoid unexpected behavior.

Imports

PyGraph
wrong
```
from retworkx import PyGraph
```
correct
```
import retworkx as rx; g = rx.PyGraph()
```
Direct import is fine, but idiomatic usage is `import retworkx as rx`

PyDiGraph

wrong

from retworkx import PyDiGraph as DiGraph

correct

import retworkx as rx; g = rx.PyDiGraph()

Avoid aliasing to avoid confusion with other graph libraries

Quickstart

Create a directed acyclic graph, add nodes and edges, and print them.

import retworkx as rx

dag = rx.PyDiGraph()
node_a = dag.add_node('A')
node_b = dag.add_child(node_a, 'B', None)
print(dag.nodes())
print(dag.edges())