Tetrad Format I/O¶

The causaliq_core.graph.io.tetrad module provides functions for reading and writing graphs in the Tetrad native format.

Format Description¶

The Tetrad format is a text-based format used by the Tetrad software suite for representing graphs: - Each line represents an edge with numbered format - Supports directed (-->) and undirected (---) edges
- Nodes are identified by names, edges by source and target nodes

Functions¶

`read(path: str) -> Union[DAG, PDAG]`¶

Read a graph from a Tetrad format file.

Parameters: - path (str): Full path name of file to read

Returns: - DAG or PDAG: Graph read from file. Returns DAG if all edges are directed, PDAG otherwise

Raises: - TypeError: If path is not a string - FileNotFoundError: If file is not found
- FileFormatError: If file format is invalid or contains syntax errors

Example:

from causaliq_core.graph.io.tetrad import read

# Read graph from Tetrad format file
graph = read("data/graph.tetrad")

`write(graph: Union[PDAG, DAG], path: str) -> None`¶

Write a graph to a Tetrad format file.

Parameters: - graph (PDAG or DAG): Graph to write - path (str): Full path name of file to create

Raises: - TypeError: If graph is not a PDAG or DAG instance, or path is not a string - OSError: If file cannot be created

Example:

from causaliq_core.graph import DAG
from causaliq_core.graph.io.tetrad import write

# Create and write a DAG
dag = DAG(['X', 'Y', 'Z'], [('X', '->', 'Y'), ('Y', '->', 'Z')])
write(dag, "output/graph.tetrad")

File Format Details¶

The Tetrad format uses numbered lines to represent edges: - Each edge line starts with a number followed by a period - Format: {number}. {source} {edge_type} {target} - Edge types: --> for directed, --- for undirected

Example Tetrad file content:

Graph Nodes:
X,Y,Z

Graph Edges:
1. X --> Y
2. Y --> Z

This represents a DAG with nodes X, Y, Z and directed edges X → Y → Z.

Compatibility¶

This module is compatible with graphs exported from: - Tetrad software suite - PCALG R package (when using Tetrad export format) - Other causal discovery tools that support Tetrad format