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YAML (.yaml, .yml)

Background

    • MIME type: application/yaml, application/openapi+yaml
    • Configuration file format.
    • Human-readable data serialization format.
    • Associates keys to values.
    • Maps unambiguously to a hash table.
    • Plain text format.

Import & Export

  • Import["file.yaml"] returns a representation of a YAML file as an Association.
  • Import["file","YAML"] returns a representation of a file as a YAML file.
  • Import["file.yaml",elem] returns the specified data representation of a YAML file.
  • Import["file",{"YAML",elem}] returns the specified data representation of a file.
  • Export["file.yaml",expr] creates a YAML file from expr.
  • See the following reference pages for full general information:
  • Import, Exportimport from or export to a file
    CloudImport, CloudExportimport from or export to a cloud object
    ImportString, ExportStringimport from or export to a string
    ImportByteArray, ExportByteArrayimport from or export to a byte array

Import Elements

  • General Import elements:
  • "Elements" list of elements and options available in this file
    "Summary"summary of the file
    "Rules"list of rules for all available elements
  • Data representation elements:
  • "Data"data as an association
  • The YAML format exports elements of an association or a list.
  • YAML treats an association as a list of sections. The keys specify the section names; the values specify the elements of a section as associations.

Import Options

Export Options

    Export Options
  • Export options include:
  • "ExpressionFormattingFunction"Automatichow expressions not supported by YAML are converted to strings
    "IndentSize"2number of spaces used for indentation
    "TerseAssociationFormatting"Falsewhether to use terse representation of associations
    "TerseListFormatting"Falsewhether to use terse representation of lists
  • "ExpressionFormattingFunction" can be set to the following values:
  • Automaticdefault conversion to string
    formany form supported by Format such as InputForm
    farbitrary function that converts an expression to a string

Examples

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Basic Examples  (2)

Import the data from a YAML string:

Wolfram Language code: input = "..."
Wolfram Language code: ImportString[input, "YAML"]

Export an association to a YAML string:

Wolfram Language code: input = <|...|>
Wolfram Language code: ExportString[input, "YAML"]

Scope  (1)

List of available elements:

Wolfram Language code: input = "..."
Wolfram Language code: ImportString[input, {"YAML", "Elements"}]

Import Elements  (2)

"Data"  (1)

Import data from a YAML string:

Wolfram Language code: input = "..."
Wolfram Language code: ImportString[input, "YAML"]

"Summary"  (1)

Export data to YAML file and get the summary:

Wolfram Language code: input = <|...|>
Wolfram Language code: Export["file.yaml", input]
Wolfram Language code: Import["file.yaml", "Summary"]

Import Options  (1)

CharacterEncoding  (1)

The character encoding can be set to any value from $CharacterEncodings:

Wolfram Language code: input = "é";
Wolfram Language code: ImportString[input, "YAML", CharacterEncoding -> "UTF8"]
Wolfram Language code: ImportString[input, "YAML", CharacterEncoding -> "ISOLatin1"]

Export Options  (4)

"ExpressionFormattingFunction"  (1)

By default, Export uses different conversion to string depending on type of expression:

Wolfram Language code: ExportString[<|"image" -> RandomImage[], "quantity" -> Quantity[100, "Kilometers"/"Hours"] |>, "YAML"]

Use "ExpressionFormattingFunction"->InputForm to get string versions of expressions suitable for input to the Wolfram Language:

Wolfram Language code: ExportString[<|"image" -> RandomImage[], "quantity" -> Quantity[100, "Kilometers"/"Hours"] |>, "YAML", "ExpressionFormattingFunction" -> InputForm]//Short

Use a function that converts expressions to strings:

Wolfram Language code: ExportString[<|"image" -> RandomImage[], "quantity" -> Quantity[100, "Kilometers"/"Hours"] |>, "YAML", "ExpressionFormattingFunction" -> SpokenString]

"IndentSize"  (1)

By default, Export indents using two spaces:

Wolfram Language code: ExportString[<|"table" -> <|"a" -> "b", "subtable" -> <|"c" -> "d"|>|>|>, "YAML"]

Indent using four spaces:

Wolfram Language code: ExportString[<|"table" -> <|"a" -> "b", "subtable" -> <|"c" -> "d"|>|>|>, "YAML", "IndentSize" -> 4]

"TerseAssociationFormatting"  (1)

By default, Export does not use terse formatting of associations:

Wolfram Language code: ExportString[<|"a" -> 1, "b" -> 2|>, "YAML"]

Use "TerseAssociationFormatting"->True to create YAML with terse representation of associations:

Wolfram Language code: ExportString[<|"a" -> 1, "b" -> 2|>, "YAML", "TerseAssociationFormatting" -> True]

"TerseListFormatting"  (1)

By default, Export does not use terse formatting of lists:

Wolfram Language code: ExportString[<|"array" -> {1, 2, 3}|>, "YAML"]

Use "TerseListFormatting"->True to create YAML with terse representation of lists:

Wolfram Language code: ExportString[<|"array" -> {1, 2, 3}|>, "YAML", "TerseListFormatting" -> True]