Pywayne CV YAML I/O

Name: pywayne-cv-tools
Rating: 76
Author: wangyendt

This module provides utilities for reading and writing OpenCV cv2.FileStorage YAML files.

Quick Start

python

from pywayne.cv.tools import read_cv_yaml, write_cv_yaml
import numpy as np

# Write to YAML file
data = {
    "camera_name": "test_camera",
    "image_width": 1920,
    "image_height": 1080,
    "calibration_matrix": np.eye(3)
}
write_cv_yaml('config.yaml', data)

# Read from YAML file
data = read_cv_yaml('config.yaml')
print(data)

Supported Data Types

Type	Handling
`int`, `float`, `str`	Written directly
`np.ndarray`	Written using `fs.write()`
`list`	Written using `FileNode_SEQ`
`dict`	Written using `FileNode_MAP`
`None`	Skipped

Reading Files

python

from pywayne.cv.tools import read_cv_yaml

# Read YAML file (returns dict or None on error)
data = read_cv_yaml('camera_config.yaml')
if data:
    print(data['camera_name'])
    print(data['image_width'])

Notes:

•Handles nested structures recursively
•Returns None if file cannot be opened
•Uses wayne_print for error messages (red/yellow colors)
•Supports both FileNode_MAP and FileNode_SEQ for dictionaries and lists
•Matrix nodes read using .mat() method

Writing Files

python

from pywayne.cv.tools import write_cv_yaml

# Write data to YAML file
data = {
    "matrix": np.eye(3),
    "vector": [1, 2, 3]
}
success = write_cv_yaml('config.yaml', data)

if success:
    print("Write successful")

Notes:

•Returns True on success, False on error
•Handles lists with empty key convention for OpenCV
•Supports unnamed sequences using empty key string
•Skips None values during write

Requirements

•cv2 (OpenCV) - For FileStorage operations
•numpy - For numpy array handling
•pywayne.tools - For wayne_print logging

API Reference

Function	Description
`read_cv_yaml(path)`	Read OpenCV YAML file, returns dict or None
`write_cv_yaml(path, data)`	Write dict to OpenCV YAML file, returns bool

File Structure Handling

The module handles OpenCV's cv2.FileNode types:

Node Type	Handling
Map	Uses `.keys()` method (requires callable)
Seq	Uses element iteration with recursive parsing
Matrix	Uses `.mat()` method
Int/Float/String	Uses `.real()`, `.int()`, `.string()` methods