Matlab.Document

PQDriverless

Not part of the Power Query standard library. This function ships in PQDriverless, an open-source package of pure M readers for binary file formats — no ODBC driver, no OLE DB provider, nothing to install. Paste the M source into a blank query, or load PQDriverless.mez as a custom connector. See Installing.

Returns a navigation table of the variables in a MATLAB MAT-file (.mat).

Syntax

Matlab.Document(
    source as binary,
    optional options as record
) as table

Remarks

Reading a .mat file normally costs a MATLAB licence or a Python interpreter with SciPy. This function decodes MAT-file level 5 directly — the format written by MATLAB v5 through v7.2 (save -v6 and save -v7) and by scipy.io.savemat.

The navigation table has one row per variable, with Name, Class, Dimensions and Data columns. Each variable converts to the M value that fits its shape:

MATLAB value	Becomes
1x1	the scalar itself (complex: a [Re, Im] record)
1xN or Nx1	a list (a char row vector becomes text)
MxN	a table with columns C1..CN (a char matrix becomes a list of texts)
more than 2 dimensions	a long table D1..Dk plus Value, column-major
1x1 struct	a record of fields
struct array	a table, one row per element, one column per field
cell array	shaped like a numeric array, elements converted recursively
sparse	a table of Row, Column, Value, 1-based, in column-major order
any empty array	null (an empty char becomes "")

Options:

• Encoding : A TextEncoding.Type or codepage number for char data stored in the legacy 8-bit form (miINT8/miUINT8), default Windows-1252. UTF-8/16/32 char data carries its own encoding and is unaffected.
• Strict : A logical (true/false). When true, tolerated malformations become errors — an unknown top-level element type, a compressed element that does not hold a matrix, or a function handle (default is false).

Examples

Example #1

Read one variable.

let
    Doc = Matlab.Document(File.Contents("C:\data\results.mat")),
    M   = Doc{[Name = "measurements"]}[Data]
in
    M

Example #2

See what's in the file and how big each variable is, before decoding anything.

let
    Doc = Matlab.Document(File.Contents("C:\data\results.mat"))
in
    Table.SelectColumns(Doc, {"Name", "Class", "Dimensions"})

Supported

MAT-file level 5 as written by MATLAB v5 through v7.2 and by scipy.io.savemat; both byte orders (IM little-endian and MI big-endian); compressed variables (v7, zlib) and uncompressed (v6); numeric storage compression, such as a double array stored as int8; all numeric classes int8-uint64, single and double; logical, char, complex, cell arrays, structs and struct arrays, objects (read as structs), sparse matrices and N-dimensional arrays.

Not supported

• v7.3 files. Those are HDF5 containers and need a different reader entirely — clear error, and re-saving with save -v7 is the fix.
• v4 files — clear error.
• Function handles and opaque/Java objects, which load as null (an error under Strict).

int64/uint64 values beyond 2⁵³ lose precision.

Metadata

Matlab.HeaderText, Matlab.ByteOrder, Matlab.SubsystemDataOffset, Matlab.VariableCount.

Category

Driverless connectors