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FiffTag

Namespace: FIFFLIB  ·  Library: FIFF Library

#include <fiff/fiff_tag.h>

class FIFFLIB::FiffTag

FIFF tag: 16-byte header (kind, type, size, next) plus payload, with typed decoders for every FIFFT_* type.

Holds the four header fields exactly as stored on disk and a QByteArray with the raw payload. Decoders convert the payload to the appropriate C++ representation: scalars via toInt / toFloat / toDouble, dense and sparse matrices via toFloatMatrix / toSparseFloatMatrix, and the structured FIFF records into their class wrappers (toFiffId, toCoordTrans, toChInfo, toChPos, toDigPoint, ...). Used by FiffStream both for streaming reads and for assembling tags before write_tag.

src/examples/ex_fiff_api/main.cpp
QFile structureFile(dir + "/sample_audvis-ave.fif");
FiffStream::SPtr stream(new FiffStream(&structureFile));
const bool opened = stream->open();
const QList<FiffDirNode::SPtr> measNodes = stream->dirtree()->dir_tree_find(FIFFB_MEAS_INFO);
std::unique_ptr<FiffTag> tag;
const bool hasNchan = measNodes.first()->find_tag(stream, FIFF_NCHAN, tag); // raw tag access
const int nchanTag = *tag->toInt();
const FiffId fileId = stream->id();
stream->close();

Inheritance​

Public Methods​

FiffTag()​

Constructs a default FiffTag.

FiffTag(p_FiffTag)​

Copy constructor.

Parameters:

  • p_FiffTag : const FiffTag & FiffTag to copy.

FiffTag(other)​

Move constructor.

Parameters:

  • other : FiffTag && FiffTag to move from; left in a valid but unspecified state.

operator=(other)​

Copy assignment operator.

Parameters:

Returns:

  • FiffTag & — Reference to this object.

operator=(other)​

Move assignment operator.

Parameters:

  • other : FiffTag && FiffTag to move from; left in a valid but unspecified state.

Returns:

  • FiffTag & — Reference to this object.

~FiffTag()​

Destroys the FiffTag.

getMatrixCoding()​

Provides information about matrix coding.

Returns:

  • fiff_int_t — Matrix coding.

isMatrix()​

Provides information if tag contains a matrix.

Returns:

  • bool — true if tag contains a matrix.

getMatrixDimensions(p_ndim, p_Dims)​

Returns matrix dimensions Refactors: fiff_get_matrix_dims (fiff_matrix.c).

Parameters:

  • p_ndim : qint32 & number of dimensions.

  • p_Dims : QVector< qint32 > & vector containing the size of each dimension.

Returns:

  • bool — true if dimensions are available.

getType()​

Provides the tag type information.

Returns:

  • fiff_int_t — the tag type.

getInfo()​

Type information as a string.

Returns:

  • QString — the tag type information.

toByte()​

to Byte Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const quint8 ** — type cast of the tag data pointer.

toUnsignedShort()​

to unsigned Short Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const quint16 ** — type cast of the tag data pointer.

toShort()​

to Short Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const qint16 ** — type cast of the tag data pointer.

toUnsignedInt()​

to Int Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const quint32 ** — type cast of the tag data pointer.

toInt()​

to Int Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const qint32 ** — type cast of the tag data pointer.

toJulian()​

to Julian Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const qint32 ** — type cast of the tag data pointer.

toFloat()​

to Float Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const float ** — type cast of the tag data pointer.

toDouble()​

to Double Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const double ** — type cast of the tag data pointer.

toString()​

to String

Returns:

  • QString — converts data to a string.

toDauPack16()​

to DauPack16 Fast access; Data are deleted if tag gets deleted, and vice versa

Returns:

  • *const qint16 ** — type cast of the tag data pointer.

toFiffID()​

to fiff ID

Returns:

toDigPoint()​

to fiff DIG POINT

Returns:

toCoordTrans()​

to fiff COORD TRANS

Returns:

toChInfo()​

to fiff CH INFO

to fiff CH INFO STRUCT

Returns:

toDirEntry()​

to fiff OLD PACK

to fiff DIR ENTRY

Returns:

  • QList< QSharedPointer<FiffDirEntry> > — List of directory entry descriptors.

toIntMatrix()​

to fiff FIFFT INT MATRIX

Returns:

  • Eigen::MatrixXi — Integer matrix.

toFloatMatrix()​

to fiff FIFFT FLOAT MATRIX

parses a fiff float matrix

Returns:

  • Eigen::MatrixXf — the parsed float matrix.

toSparseFloatMatrix()​

to sparse fiff FIFFT FLOAT MATRIX

parses a sparse fiff float matrix and returns a double sparse matrix to make sure only double is used

Returns:

  • Eigen::SparseMatrix< double > — a sparse double matrix which is newly created from the parsed float; empty if the tag is no valid sparse float matrix (see FiffSparseMatrix::fiff_get_float_sparse_matrix).

Static Methods​

convert_ch_pos(pos)​

Convert coil position descriptor.

Parameters:

  • pos : *FiffChPos ** coil position descriptor to convert.

convert_matrix_from_file_data(tag)​

Machine dependent data type conversions (tag info only).

from_endian defines the byte order of the input to_endian defines the byte order of the output

Either of these may be specified as FIFFV_LITTLE_ENDIAN, FIFFV_BIG_ENDIAN, or FIFFV_NATIVE_ENDIAN. The last choice means that the native byte order value will be substituted here before proceeding

Parameters:

  • tag : const FiffTag::UPtr & Matrix tag whose dimensions, indices and data are byte-swapped in place; non-matrix tags are left untouched.

convert_matrix_to_file_data(tag)​

Convert matrix data before writing to a file inside a fiff tag.

Parameters:

  • tag : const FiffTag::UPtr & matrix data to convert.

convert_tag_data(tag, from_endian, to_endian)​

Machine dependent data type conversions (tag info only).

from_endian defines the byte order of the input to_endian defines the byte order of the output

Either of these may be specified as FIFFV_LITTLE_ENDIAN, FIFFV_BIG_ENDIAN, or FIFFV_NATIVE_ENDIAN. The last choice means that the native byte order value will be substituted here before proceeding

Parameters:

  • tag : const FiffTag::UPtr & matrix data to convert.

  • from_endian : int from endian encoding.

  • to_endian : int to endian encoding.

fiff_type_fundamental(type)​

These return information about a fiff type.

Parameters:

  • type : fiff_int_t The fiff data type to query.

Returns:

  • fiff_int_t — fiff type.

fiff_type_base(type)​

These return information about fiff type base.

Parameters:

  • type : fiff_int_t The fiff data type to query.

Returns:

  • fiff_int_t — fiff type.

fiff_type_matrix_coding(type)​

These return information about the matrix coding.

Parameters:

  • type : fiff_int_t The fiff data type to query.

Returns:

  • fiff_int_t — matrix coding.

storageSize()​

Size of the on-disk tag info header: kind + type + size + next = 4 x fiff_int_t.

This corresponds to the old sizeof(fiffTagRec) - sizeof(fiff_data_t *).

Returns:

  • qint32 — the byte size of the on-disk tag info header.

Example​

Used in examples​

ex_fiff_api​

FIFF library: measurement info, channels, digitizer, transforms, projectors, covariance, events,.

src/examples/ex_fiff_api/main.cpp, line 209
FiffStream::SPtr stream(new FiffStream(&structureFile));
const bool opened = stream->open();
const QList<FiffDirNode::SPtr> measNodes = stream->dirtree()->dir_tree_find(FIFFB_MEAS_INFO);
std::unique_ptr<FiffTag> tag;
const bool hasNchan = measNodes.first()->find_tag(stream, FIFF_NCHAN, tag); // raw tag access
const int nchanTag = *tag->toInt();
const FiffId fileId = stream->id();
stream->close();
ok &= expect(opened && measNodes.size() == 1 && hasNchan && nchanTag == 376 && !fileId.isEmpty() && fileId.version > 0,
             "FiffStream/FiffDirNode/FiffTag/FiffId: the FIFF_NCHAN tag of the measurement block reads 376");

Authors of this file​