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MTX (.mtx)

  • Import and Export fully support the Matrix Market file format.

Background & Context

    • Matrix Market matrix format.
    • Used for exchanging and storing test matrices.
    • Plain text format.
    • File format of the NIST Matrix Market collection of standard test matrices.
    • Stores numerical or pattern matrices in a dense ("array format") or sparse ("coordinate format") representation.
    • Developed in 1996 by R. Boisvert, R. Pozo, K. Remington, and J. Dongarra.
    • Maintained by the US National Institute of Standards and Technology (NIST).

Import & Export

  • Import["file.mtx"] imports matrix data from a Matrix Market file.
  • The Wolfram Language converts "array format" files to packed arrays and "coordinate format" files to sparse arrays.
  • Import["file.mtx",elem] imports the specified element.
  • The import format can be specified with Import["file","MTX"] or Import["file",{"MTX",elem,…}].
  • Export["file.mtx",expr] exports any numerical or pattern matrix to a Matrix Market file.
  • Export["file.mtx",expr,elem] creates a Matrix Market file by treating expr as specifying element elem.
  • 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"matrix data given as a packed or sparse array
    "Graphics"a visual representation of the values of the matrix elements
  • Import uses the "Data" element by default.
  • Import["file.mtx","Graphics"] uses MatrixPlot to render the matrix structure as graphics.
  • Data descriptor elements:
  • "DataFormat"matrix data type
    "Dimensions"matrix dimensions
  • Metainformation elements:
  • "Comments"user comments stored in the file
    "MatrixStructure"symmetry properties of the matrix
  • Possible values for "MatrixStructure" are:
  • "Hermitian"matrix that is equal to its own conjugate transpose
    "General"matrix without transposition symmetry
    "SkewSymmetric"matrix whose transpose is also its negative
    "Symmetric"matrix that is equal to its transpose

Import Options

  • Details of options...

Examples

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Basic Examples  (2)

Import a sparse matrix from an MTX sample file:

Import data as visual graphics:

Export a 2×2 matrix to MTX:

Scope  (3)

Import  (2)

List available Import elements:

Import dimensions of a sparse array:

Export  (1)

Export a NumericArray to MTX:

Import Elements  (7)

"Comments"  (1)

Import comments from an MTX file:

"Data"  (1)

Import data from an MTX file:

"DataFormat"  (1)

Import matrix data type:

"Dimensions"  (1)

Import matrix dimensions:

"Graphics"  (1)

Get a visual representation of a matrix from an MTX file:

"MatrixStructure"  (1)

Import symmetry properties of the matrix:

"Summary"  (1)

Import the summary of the file:

Export Options  (5)

"Comments"  (3)

By default, the following comment is written to the MTX file:

Specify the value of "Comments":

Multiple lines of comments can be specified as a list of strings:

"MatrixStructure"  (2)

By default, Export automatically determines the symmetry of the matrix:

Use the "MatrixStructure" option to overwrite the default behavior: