pydot-ng: Python interface to Graphviz's Dot (Archived)

2.0.0 · abandoned · verified Wed Apr 15

Pydot-ng is an archived Python interface to Graphviz's Dot language, enabling programmatic creation, manipulation, and rendering of graphs. It was originally created to provide Python 2 and 3 compatibility as a fork of the original pydot. The last stable version is 2.0.0, released in October 2018. This project is no longer actively maintained, and users are strongly advised to use the actively developed `pydot` library instead.

Warnings

breaking The pydot-ng project is archived and read-only. It is no longer maintained. Users should migrate to the actively developed `pydot` library (PyPI: `pydot`, GitHub: `pydot/pydot`).
Fix: Migrate your codebase to use the `pydot` library. Install with `pip install pydot` and update imports from `pydot_ng` to `pydot`.
gotcha Graphviz (the underlying graph visualization software) must be installed separately on your system, and its executable files (e.g., `dot`, `neato`) must be accessible via your system's PATH environment variable. Pydot-ng (and pydot) will not work without a correctly configured Graphviz installation.
Fix: Install Graphviz from its official website (graphviz.org) or via your system's package manager (e.g., `sudo apt-get install graphviz` on Debian/Ubuntu, `brew install graphviz` on macOS). Then, ensure the directory containing the Graphviz executables is added to your system's PATH.
deprecated pydot-ng was a fork of pydot to support both Python 2 and 3. The original `pydot` project has since been updated to support Python 3+ and the `pydot-ng` repository explicitly directs users to `pydot`. Continued use of `pydot-ng` may lead to compatibility issues with newer Python versions or lack of bug fixes.
Fix: Switch to using the `pydot` library, which is actively maintained and compatible with modern Python versions (e.g., Python 3.9+).
gotcha Older versions of pydot-ng might have issues locating Graphviz executables, particularly on Windows, sometimes looking for `.bat` files instead of `.exe`.
Fix: Ensure Graphviz is properly installed and its `bin` directory is in the system PATH. For persistent issues, consider using the active `pydot` library, which likely has improved executable detection.

Install

pip install pydot-ng Install pydot-ng

Imports

pydot_ng
wrong:
```
import pydot
```
correct:
```
import pydot_ng
```
While 'import pydot_ng as pydot' was a common pattern for API compatibility with the original pydot, direct import is 'pydot_ng'. However, given the project's archived status, it's recommended to use the actively maintained `pydot` library directly (i.e., `import pydot`).
Graph
```
from pydot_ng import Graph
```
This would be the correct way to import the Graph class from pydot-ng, though using `import pydot_ng as pydot` and then `pydot.Graph` was more common for compatibility.
Node
```
from pydot_ng import Node
```
This would be the correct way to import the Node class from pydot-ng.
Edge
```
from pydot_ng import Edge
```
This would be the correct way to import the Edge class from pydot-ng.

Quickstart

This quickstart demonstrates how to create a simple directed graph with nodes and edges using pydot-ng and save it as a PNG image. It includes important warnings about the project's archived status and the Graphviz system dependency. For new projects, use the 'pydot' library.

import pydot_ng as pydot
import os

# NOTE: pydot-ng is archived. It is highly recommended to use 'pydot' instead.
# For Graphviz to work, ensure it is installed on your system and 'dot' is in your PATH.
# On Linux: sudo apt-get install graphviz
# On macOS: brew install graphviz
# On Windows: Download from graphviz.org and add 'bin' to PATH.

# Create a graph
graph = pydot.Dot('my_graph', graph_type='digraph')

# Add nodes
node_a = pydot.Node('A', style='filled', fillcolor='red')
node_b = pydot.Node('B', style='filled', fillcolor='green')
node_c = pydot.Node('C', style='filled', fillcolor='blue')

graph.add_node(node_a)
graph.add_node(node_b)
graph.add_node(node_c)

# Add edges
graph.add_edge(pydot.Edge(node_a, node_b))
graph.add_edge(pydot.Edge(node_b, node_c, label='Connects'))

# Save the graph to a file
try:
    # Using a temporary file for demonstration
    output_file = 'quickstart_graph.png'
    graph.write_png(output_file)
    print(f"Graph saved to {output_file}")
except Exception as e:
    print(f"Error generating graph: {e}")
    print("Please ensure Graphviz is installed and its 'dot' executable is in your system's PATH.")

# Clean up the generated file for demonstration purposes (optional)
# if os.path.exists(output_file):
#     os.remove(output_file)

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