Python YAML

Python YAML

YAML (YAML Ain't Markup Language) is a human-readable data serialization format. It is often used for configuration files and data exchange between different programming languages. Python provides a YAML library that makes it easy to work with YAML files in Python. This article explores the Python YAML library and demonstrates how to use it to read and write YAML files.

Installation

The Python YAML library, called PyYAML, can be installed using pip:

pip install pyyaml

Reading YAML Files

To read a YAML file in Python, we need to import the PyYAML library and use the load() method:

import yaml
with open('data.yaml', 'r') as file:
    data = yaml.load(file, Loader=yaml.FullLoader)
print(data)

The above code reads the contents of the 'data.yaml' file and loads it into a Python data structure. By specifying Loader=yaml.FullLoader, we ensure that the YAML file is parsed using the latest YAML specification.

Accessing Data

Once the YAML file is loaded into a Python data structure, we can access the data using regular Python syntax. For example, if the YAML file contains a list of names, we can access them as follows:

names = data['names']
print(names)

We can also access nested data using dot notation. If the YAML file has a structure like this:

person:
    name: John
    age: 30

We can access the person's name and age as follows:

person = data['person']
name = person['name']
age = person['age']
print(name)
print(age)

Writing YAML Files

To write data to a YAML file in Python, we can use the dump() method:

import yaml
data = {
    'name': 'John',
    'age': 30,
    'occupation': 'Engineer'
}
with open('data.yaml', 'w') as file:
    yaml.dump(data, file)

This code writes the contents of the data dictionary to a YAML file named 'data.yaml' using the dump() method.

YAML Formatting

By default, the dump() method outputs YAML data with the default indentation and formatting. However, we can customize the formatting using the default_flow_style argument. For example, to output the data in a more compact style with inline structures, we can set default_flow_style=True:

import yaml
data = {
    'name': 'John',
    'age': 30,
    'occupation': 'Engineer'
}
with open('data.yaml', 'w') as file:
    yaml.dump(data, file, default_flow_style=True)

This will result in a YAML file with inline structures:

{age: 30, name: John, occupation: Engineer}

Conclusion

The Python YAML library (PyYAML) makes it easy to work with YAML files in Python. We can read and parse YAML files using the load() method, access the data using Python syntax, and write data to YAML files using the dump() method. With PyYAML, we can seamlessly integrate YAML files into our Python applications and scripts.

By understanding how to use PyYAML, we can efficiently handle configuration files, data exchange between different systems, and other YAML-related tasks in Python.