A full-featured YAML processing framework for Python.

The documentation is available on the PyYAML website or in the form of GitHub flavoured markdown.

pip install pyyaml

pip install git+https://github.com/yaml/pyyaml.git@master

or checkout the repository, or extract the .tar.gz and navigate inside and run:

python setup.py install

By default, the setup.py script checks whether LibYAML is installed and if so, builds and installs LibYAML bindings.

When LibYAML bindings are installed, you may use fast C-based parser and emitter as follows:

yaml.load(stream, Loader=yaml.CLoader)
yaml.dump(data, Dumper=yaml.CDumper)

python setup.py --with-libyaml install

python setup.py --without-libyaml install

PyYAML includes a comprehensive test suite. To run the tests:

python setup.py test

Your default and safest choice for YAML streams.

WARNING: CVE reference, etc. from wiki page.

Can load Python objects:

e.g. SafeLoader etc ...

Mention that these are the keyword arguments of the Dumper class and subclasses.

• the python object to serialise

Applies to safe_dump(), safe_dump_all() dump(), dump_all functions and the Dumper class

• IOObject - anything with a .write(), will be written to
• None - returns a string.

• Type[Dumper] class/subclass of Dumper ...

• Optional[bool]
  • True - what true does
  • False - what false does
  • None - what None does

Mention that these are the keyword arguments of the Loader class and subclasses.

• YAML Spec 1.1 - Mostly supported.
• YAML Spec 1.2 - Partial Support.
• YAML Spec 1.3 - Not Supported Yet.

Why does

import yaml
document = """
  a: 1
  b:
    c: 3
    d: 4
"""
print(yaml.dump(yaml.load(document)))

give

a: 1
b: {c: 3, d: 4}

(see #18, #24)?

It's a correct output despite the fact that the style of the nested mapping is different.

By default, PyYAML chooses the style of a collection depending on whether it has nested collections. If a collection has nested collections, it will be assigned the block style. Otherwise it will have the flow style.

If you want collections to be always serialized in the block style, set the parameter default_flow_style of dump() to False. For instance,

>>> print(yaml.dump(yaml.load(document), default_flow_style=False))
a: 1
b:
  c: 3
  d: 4

Starting from the 3.08 release, PyYAML and LibYAML bindings provide a complete support for Python 3. Python 2 support was dropped in the 6.0 release. This is a short outline of differences in PyYAML API between Python 2 and Python 3 versions.

In Python 2:

• str objects are converted into !!str, !!python/str or !binary nodes depending on whether the object is an ASCII, UTF-8 or binary string.
• unicode objects are converted into !!python/unicode or !!str nodes depending on whether the object is an ASCII string or not.
• yaml.dump(data) produces the document as a UTF-8 encoded str object.
• yaml.dump(data, encoding=('utf-8'|'utf-16-be'|'utf-16-le')) produces a str object in the specified encoding.
• yaml.dump(data, encoding=None) produces a unicode object.

In Python 3:

• str objects are converted to !!str nodes.
• bytes objects are converted to !!binary nodes.
• For compatibility reasons, !!python/str and !python/unicode tags are still supported and the corresponding nodes are converted to str objects.
• yaml.dump(data) produces the document as a str object.
• yaml.dump(data, encoding=('utf-8'|'utf-16-be'|'utf-16-le')) produces a bytes object in the specified encoding.

• For more information, check the PyYAML homepage.

• PyYAML tutorial and reference.

• Discuss PyYAML with the maintainers on Matrix at https://matrix.to/#/#pyyaml:yaml.io or IRC #pyyaml irc.libera.chat

• Submit bug reports and feature requests to the PyYAML bug tracker.

The PyYAML module was written by Kirill Simonov [email protected]. It is currently maintained by the YAML and Python communities.

PyYAML is released under the MIT license.

See the file LICENSE for more details.

Please report any security vulnerabilities to :