Yaml Python Download For Mac

PyYAML supports standard YAML tags and provides Python-specific tags that allow to represent an arbitrary Python object. PyYAML is applicable for a broad range of tasks from complex configuration files to object serialization and persistance. Tour Start here for a quick overview of the site Help Center Detailed answers to any questions you might have Meta Discuss the workings and policies of this site. This Mac download was scanned by our built-in antivirus and was rated as clean. PyYAML is a YAML parser and emitter for Python. YAML is a data serialization format designed for human readability and interaction with scripting languages.

1. Python Yaml Tutorial

PyYAML Documentation PyYAML is a YAML parser and emitter for Python. Installation Simple install: pip install pyyaml To install from source, download the source package PyYAML-3.13.tar.gz and unpack it.

Go to the directory PyYAML-3.13 and run: $ python setup.py install If you want to use LibYAML bindings, which are much faster than the pure Python version, you need to download and install. Then you may build and install the bindings by executing $ python setup.py -with-libyaml install In order to use based parser and emitter, use the classes CParser and CEmitter. For instance. Python 3 support Starting from the 3.08 release, PyYAML and LibYAML bindings provide a complete support for Python 3. 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.

Tutorial Start with importing the yaml package. Note that the ability to construct an arbitrary Python object may be dangerous if you receive a YAML document from an untrusted source such as the Internet. The function yaml.safeload limits this ability to simple Python objects like integers or lists. A python object can be marked as safe and thus be recognized by yaml.safeload.

To do this, derive it from yaml.YAMLObject (as explained in section Constructors, representers, resolvers) and explicitly set its class property yamlloader to yaml.SafeLoader. Dumping YAML The yaml.dump function accepts a Python object and produces a YAML document. YAML syntax A good introduction to the YAML syntax is. You may also check. Note that it is focused on a Ruby implementation and uses the old YAML 1.0 syntax.

Here we present most common YAML constructs together with the corresponding Python objects. Documents YAML stream is a collection of zero or more documents. An empty stream contains no documents. Documents are separated with -. Documents may optionally end with.

A single document may or may not be marked with -. Example of an implicit document. Each style has its own quirks.

A plain scalar does not use indicators to denote its start and end, therefore it’s the most restricted style. Its natural applications are names of attributes and parameters. Using single-quoted scalars, you may express any value that does not contain special characters. No escaping occurs for single quoted scalars except that a pair of adjacent quotes ' is replaced with a lone single quote '. Double-quoted is the most powerful style and the only style that can express any scalar value. Double-quoted scalars allow escaping. Using escaping sequences x.

and u., you may express any ASCII or Unicode character. There are two kind of block scalar styles: literal and folded. The literal style is the most suitable style for large block of text such as source code. The folded style is similar to the literal style, but two adjacent non-empty lines are joined to a single line separated by a space character.

Aliases Note that PyYAML does not yet support recursive objects. Using YAML you may represent objects of arbitrary graph-like structures. If you want to refer to the same object from different parts of a document, you need to use anchors and aliases. Anchors are denoted by the & indicator while aliases are denoted by ``.

For instance, the document. Plain scalars without explicitly defined tags are subject to implicit tag resolution.

The scalar value is checked against a set of regular expressions and if one of them matches, the corresponding tag is assigned to the scalar. PyYAML allows an application to add custom implicit tag resolvers. YAML tags and Python types The following table describes how nodes with different tags are converted to Python objects. Compose(stream) parses the given stream and returns the root of the representation graph for the first document in the stream. If there are no documents in the stream, it returns None. Composeall(stream) parses the given stream and returns a sequence of representation graphs corresponding to the documents in the stream.

Serialize(node, stream=None) serializes the given representation graph into the stream. If stream is None, it returns the produced stream. Serializeall(node, stream=None) serializes the given sequence of representation graphs into the given stream.

If stream is None, it returns the produced stream. Load(stream) parses the given stream and returns a Python object constructed from for the first document in the stream. If there are no documents in the stream, it returns None. Loadall(stream) parses the given stream and returns a sequence of Python objects corresponding to the documents in the stream. Safeload(stream) parses the given stream and returns a Python object constructed from for the first document in the stream. If there are no documents in the stream, it returns None.

Safeload recognizes only standard YAML tags and cannot construct an arbitrary Python object. A python object can be marked as safe and thus be recognized by yaml.safeload. To do this, derive it from yaml.YAMLObject (as explained in section Constructors, representers, resolvers) and explicitly set its class property yamlloader to yaml.SafeLoader. Safeloadall(stream) parses the given stream and returns a sequence of Python objects corresponding to the documents in the stream. Safeloadall recognizes only standard YAML tags and cannot construct an arbitrary Python object.

Dump(data, stream=None) serializes the given Python object into the stream. If stream is None, it returns the produced stream. Dumpall(data, stream=None) serializes the given sequence of Python objects into the given stream.

If stream is None, it returns the produced stream. Each object is represented as a YAML document. Safedump(data, stream=None) serializes the given Python object into the stream.

If stream is None, it returns the produced stream. Safedump produces only standard YAML tags and cannot represent an arbitrary Python object. Safedumpall(data, stream=None) serializes the given sequence of Python objects into the given stream. If stream is None, it returns the produced stream.

Each object is represented as a YAML document. Safedumpall produces only standard YAML tags and cannot represent an arbitrary Python object. Addconstructor(tag, constructor) specifies a constructor for the given tag. A constructor is a function that converts a node of a YAML representation graph to a native Python object.

A constructor accepts an instance of Loader and a node and returns a Python object. Addmulticonstructor(tagprefix, multiconstructor) specifies a multiconstructor for the given tagprefix. A multi-constructor is a function that converts a node of a YAML representation graph to a native Python object. A multi-constructor accepts an instance of Loader, the suffix of the node tag, and a node and returns a Python object.

Addrepresenter(datatype, representer) specifies a representer for Python objects of the given datatype. A representer is a function that converts a native Python object to a node of a YAML representation graph. A representer accepts an instance of Dumper and an object and returns a node. Addmultirepresenter(basedatatype, multirepresenter) specifies a multirepresenter for Python objects of the given basedatatype or any of its subclasses. A multi-representer is a function that converts a native Python object to a node of a YAML representation graph. A multi-representer accepts an instance of Dumper and an object and returns a node. The flowstyle flag indicates if a collection is block or flow.

Python Yaml Tutorial

The possible values are None, True, False. The style flag of a scalar event indicates the style of the scalar. Possible values are None, , ' , ', ' ', '. The implicit flag of a collection start event indicates if the tag may be omitted when the collection is emitted. The implicit flag of a scalar event is a pair of boolean values that indicate if the tag may be omitted when the scalar is emitted in a plain and non-plain style correspondingly.

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