How to Convert Python Dictionary to YAML

In this tutorial, you’ll learn various methods to convert Python dictionaries to YAML.

We’ll explore popular libraries like PyYAML and ruamel.yaml, as well as alternative methods using omegaconf, json2yaml, custom serialization, and Jinja2 templates.

 

 

Using PyYAML

To convert a dictionary to YAML using PyYAML, use the dump() function:

import yaml
data = {
    'name': 'Amr',
    'age': 30,
    'city': 'Cairo',
    'hobbies': ['reading', 'swimming', 'coding']
}
yaml_string = yaml.dump(data, default_flow_style=False)
print(yaml_string)

Output:

age: 30
city: Cairo
hobbies:
- reading
- swimming
- coding
name: Amr

The default_flow_style=False argument ensures that the output is in block style to make it readable for nested structures.

 

Using ruamel.yaml

To use ruamel.yaml for converting a dictionary to YAML, create a YAML object and use its dump() method:

from ruamel.yaml import YAML

data = {
  'database': {
      'host': 'localhost',
      'port': 5432,
      'user': 'Fatma',
      'password': 'secret'
  },
  'debug': True,
  'logging': {
      'level': 'INFO',
      'file': '/var/log/app.log'
  }
}
yaml = YAML()
with open('output.yaml', 'w') as file:
  yaml.dump(data, file)

Output(File content):

database:
  host: localhost
  port: 5432
  user: Fatma
  password: secret
debug: true
logging:
  level: INFO
  file: /var/log/app.log

ruamel.yaml preserves the order of keys and provides more control over the output format.

 

Using omegaconf

To convert a dictionary to YAML using omegaconf, create an OmegaConf object and use the to_yaml() method:

from omegaconf import OmegaConf
data = {
    'project': 'MyApp',
    'version': '1.0.0',
    'settings': {
        'debug': False,
        'max_connections': 100,
        'timeout': 30
    },
    'features': ['auth', 'api', 'notifications']
}
conf = OmegaConf.create(data)
yaml_string = OmegaConf.to_yaml(conf)
print(yaml_string)

Output:

project: MyApp
version: '1.0.0'
settings:
  debug: false
  max_connections: 100
  timeout: 30
features:
- auth
- api
- notifications

omegaconf is useful when you need to work with configuration files that may be modified at runtime.

 

Using Custom Serialization

For more control over the YAML output, you can implement a custom serialization function:

Create a custom function to convert your dictionary to YAML format:

def dict_to_yaml(data, indent=0):
  yaml_str = ""
  for key, value in data.items():
      yaml_str += "  " * indent + str(key) + ": "
      if isinstance(value, dict):
          yaml_str += "\n" + dict_to_yaml(value, indent + 1)
      elif isinstance(value, list):
          yaml_str += "\n" + "".join(["  " * (indent + 1) + "- " + str(item) + "\n" for item in value])
      else:
          yaml_str += str(value) + "\n"
  return yaml_str
data = {
  'person': {
      'name': 'Nour',
      'age': 28,
      'skills': ['Python', 'YAML', 'Docker']
  },
  'company': 'TechCorp',
  'position': 'Developer'
}
print(dict_to_yaml(data))

Output:

person: 
  name: Nour
  age: 28
  skills: 
  - Python
  - YAML
  - Docker
company: TechCorp
position: Developer

This custom function gives you full control over the YAML formatting.

 

Using jinja2 Templates

For more complex YAML structures, you can use Jinja2 templates to generate YAML from your dictionary:

Create a Jinja2 template and render it with your dictionary data:

from jinja2 import Template
yaml_template = """
application:
  name: {{ app_name }}
  version: {{ version }}
database:
  host: {{ db.host }}
  port: {{ db.port }}
  username: {{ db.username }}
settings:
  debug: {{ debug }}
  log_level: {{ log_level }}
features:
{% for feature in features %} - {{ feature }}
{% endfor %}
"""
data = {
    'app_name': 'MyAwesomeApp',
    'version': '2.1.0',
    'db': {
        'host': 'db.example.com',
        'port': 5432,
        'username': 'Aisha'
    },
    'debug': False,
    'log_level': 'INFO',
    'features': ['user_management', 'reporting', 'analytics']
}
template = Template(yaml_template)
yaml_output = template.render(data)
print(yaml_output)

Output:

application:
  name: MyAwesomeApp
  version: 2.1.0
database:
  host: db.example.com
  port: 5432
  username: Aisha
settings:
  debug: False
  log_level: INFO
features:
  - user_management
  - reporting
  - analytics