Stores values of a UVW column in a compressed way. More...

#include <UvwFile.h>

Public Member Functions
	UvwFile () noexcept=default

	UvwFile (UvwFile &&source) noexcept

	~UvwFile () noexcept

UvwFile &	operator= (UvwFile &&rhs)

void	WriteUvw (uint64_t row, size_t antenna1, size_t antenna2, const double *uvw)
	Write a single row to the column.

void	ReadUvw (uint64_t row, size_t antenna1, size_t antenna2, double *uvw)
	Read a single row.

void	Close ()

uint64_t	NRows () const

std::string	Filename () const

Static Public Member Functions
static UvwFile	CreateNew (const std::string &filename)
	Create a new UVW file on disk with the given filename.

static UvwFile	OpenExisting (const std::string &filename)
	Open an already existing UVW file from disk with the given filename.

Private Member Functions
	UvwFile (const std::string &filename)
	Create a new file on disk.

	UvwFile (const std::string &filename, bool)
	Open an existing file from disk.

void	StoreOrCheck (size_t antenna, const std::array< double, 3 > &antenna_uvw)
	If this block does not have a value for the specified antenna, store the uvw value for it.

void	ActivateBlock (size_t block)

void	ReadActiveBlock ()

void	WriteActiveBlock ()

void	ReadHeader ()

void	WriteHeader ()

bool	IsSet (size_t antenna) const

Static Private Member Functions
static bool	AreNear (std::array< double, 3 > a, std::array< double, 3 > b)

static bool	AreNear (double a, double b)

static std::string	UvwAsString (const std::array< double, 3 > &uvw)

Private Attributes
BufferedColumnarFile	file_

uint64_t	n_rows_
	Number of rows in the Uvw column.

uint64_t	rows_per_block_
	A "block" is a contiguous number of baselines that together form one timestep.

uint64_t	active_block_

size_t	reference_antenna_

size_t	start_antenna_2_
	This value is used to determine the first baseline in the data, which is the baseline (reference_antenna_, start_antenna_2_).

size_t	n_antennas_

std::vector< std::array< double, 3 > >	block_uvws_
	UVW for each antenna in the block.

bool	block_is_changed_

Static Private Attributes
static constexpr size_t	kHeaderSize
	The header: char[8] "Uvw-col\0" (=kMagicHeaderTag) uint64_t rows_per_block uint64_t reference_antenna uint64_t n_antenna.

static constexpr const char	kMagicHeaderTag [8]

static constexpr std::array< double, 3 >	kUnsetPosition

Detailed Description

Stores values of a UVW column in a compressed way.

Instead of storing a UVW value per baseline, it stores one per antenna. It uses the fact that:

baseline_uvw = antenna2_uvw - antenna1_uvw.

By taking the first written antenna as reference antenna and storing the relative UVW distance of the other antennas towards the reference antenna, the baseline uvws can be reconstructed.

A small downside is that this requires the measurement set to be "reasonably" ordered: every timestep should have the same baselines in the same order. Also, it requires the baselines to be ordered such that a relation to the reference antenna can be made. A measurement set that is ordered either by antenna1 or antenna2 for which no baselines have been removed satisfies this. Removing an entire antenna is fine.

Example of acceptable antenna lists:

[0,0] ; [0,1] ; [0,2] ; [1,1] ; [1,2] ; [2,2] Ordered by antenna1, no missing baselines, no missing antennas.
[0,1] ; [0,2] ; [1,2] Ordered by antenna1, only auto-correlations are missing, no missing antennas.
[0,0] ; [1,0] ; [2,0] ; [1,1] ; [2,1] ; [2,2] Ordered by antenna2, only auto-correlations are missing, no missing antennas.
[1,3] ; [1,4] ; [3,4] Ordered by antenna1, misses antenna 0 and 2.

An example of a baseline ordering that is not accepted:

[1, 2] ; [3, 4] The class will use 1 as reference antenna and calculate antenna 2 relative to that. However, it can't store 3 or 4 relative to 1.

Definition at line 49 of file UvwFile.h.

Constructor & Destructor Documentation

◆ UvwFile() [1/4]

casacore::UvwFile::UvwFile ( )

defaultnoexcept

Referenced by CreateNew(), and OpenExisting().

◆ UvwFile() [2/4]

casacore::UvwFile::UvwFile ( UvwFile && source )

inlinenoexcept

Definition at line 53 of file UvwFile.h.

References casacore::RowBasedFile::n_rows_.

◆ ~UvwFile()

casacore::UvwFile::~UvwFile ( )

inlinenoexcept

Definition at line 73 of file UvwFile.h.

References Close().

◆ UvwFile() [3/4]

casacore::UvwFile::UvwFile ( const std::string & filename )

inlineprivate

Create a new file on disk.

Definition at line 224 of file UvwFile.h.

◆ UvwFile() [4/4]

casacore::UvwFile::UvwFile	(	const std::string &	filename,
		bool
	)

inlineprivate

Open an existing file from disk.

The last parameter is a dummy parameter to distinguish it from the creating constructor.

Setting the size of block_uvws_ here, saves an extra size check in ActivateBlock().

Definition at line 232 of file UvwFile.h.

References active_block_, block_uvws_, file_, kUnsetPosition, n_antennas_, n_rows_, casacore::VarBufferedColumnarFile< BufferSize >::NRows(), ReadHeader(), reference_antenna_, and rows_per_block_.

Member Function Documentation

◆ ActivateBlock()

void casacore::UvwFile::ActivateBlock ( size_t block )

inlineprivate

Definition at line 279 of file UvwFile.h.

References active_block_, block_is_changed_, ReadActiveBlock(), and WriteActiveBlock().

Referenced by ReadUvw(), and WriteUvw().

◆ AreNear() [1/2]

static bool casacore::UvwFile::AreNear	(	double	a,
		double	b
	)

inlinestaticprivate

Definition at line 355 of file UvwFile.h.

◆ AreNear() [2/2]

static bool casacore::UvwFile::AreNear	(	std::array< double, 3 >	a,
		std::array< double, 3 >	b
	)

inlinestaticprivate

Definition at line 352 of file UvwFile.h.

References AreNear().

Referenced by AreNear(), and StoreOrCheck().

◆ Close()

void casacore::UvwFile::Close ( )

inline

Definition at line 203 of file UvwFile.h.

References block_is_changed_, block_uvws_, casacore::VarBufferedColumnarFile< BufferSize >::Close(), file_, casacore::VarBufferedColumnarFile< BufferSize >::IsOpen(), n_antennas_, n_rows_, rows_per_block_, WriteActiveBlock(), and WriteHeader().

Referenced by operator=(), and ~UvwFile().

◆ CreateNew()

static UvwFile casacore::UvwFile::CreateNew ( const std::string & filename )

inlinestatic

Create a new UVW file on disk with the given filename.

Definition at line 100 of file UvwFile.h.

References UvwFile().

◆ Filename()

std::string casacore::UvwFile::Filename ( ) const

inline

Definition at line 218 of file UvwFile.h.

References file_, and casacore::VarBufferedColumnarFile< BufferSize >::Filename().

◆ IsSet()

bool casacore::UvwFile::IsSet ( size_t antenna ) const

inlineprivate

Definition at line 348 of file UvwFile.h.

References block_uvws_, and kUnsetPosition.

Referenced by StoreOrCheck(), and WriteUvw().

◆ NRows()

uint64_t casacore::UvwFile::NRows ( ) const

inline

Definition at line 217 of file UvwFile.h.

References n_rows_.

◆ OpenExisting()

static UvwFile casacore::UvwFile::OpenExisting ( const std::string & filename )

inlinestatic

Open an already existing UVW file from disk with the given filename.

Definition at line 107 of file UvwFile.h.

References UvwFile().

◆ operator=()

UvwFile & casacore::UvwFile::operator= ( UvwFile && rhs )

inline

Definition at line 75 of file UvwFile.h.

References active_block_, block_is_changed_, block_uvws_, Close(), file_, n_antennas_, n_rows_, reference_antenna_, rows_per_block_, and start_antenna_2_.

◆ ReadActiveBlock()

void casacore::UvwFile::ReadActiveBlock ( )

inlineprivate

Definition at line 290 of file UvwFile.h.

References active_block_, block_uvws_, file_, kUnsetPosition, n_antennas_, casacore::VarBufferedColumnarFile< BufferSize >::NRows(), casacore::VarBufferedColumnarFile< BufferSize >::Read(), and reference_antenna_.

Referenced by ActivateBlock().

◆ ReadHeader()

void casacore::UvwFile::ReadHeader ( )

inlineprivate

Definition at line 326 of file UvwFile.h.

References file_, kHeaderSize, kMagicHeaderTag, n_antennas_, casacore::VarBufferedColumnarFile< BufferSize >::ReadHeader(), reference_antenna_, and rows_per_block_.

Referenced by UvwFile().

◆ ReadUvw()

void casacore::UvwFile::ReadUvw	(	uint64_t	row,
		size_t	antenna1,
		size_t	antenna2,
		double *	uvw
	)

inline

Read a single row.

This may be done in random order, but is most efficient when reading a file contiguously.

Parameters

row	denotes the row in the Casacore measurement set to be read.

Definition at line 185 of file UvwFile.h.

References ActivateBlock(), block_uvws_, file_, casacore::VarBufferedColumnarFile< BufferSize >::IsOpen(), n_antennas_, n_rows_, and rows_per_block_.

Referenced by casacore::UvwStManColumn::getArrayV().

◆ StoreOrCheck()

void casacore::UvwFile::StoreOrCheck	(	size_t	antenna,
		const std::array< double, 3 > &	antenna_uvw
	)

inlineprivate

If this block does not have a value for the specified antenna, store the uvw value for it.

If it does have a value, the value is checked. This check has a relatively high tolerance (1e-5, fractionally) because it is only there to catch "significant" errors caused by e.g. writing in the wrong order.

Definition at line 262 of file UvwFile.h.

References AreNear(), block_is_changed_, block_uvws_, IsSet(), kUnsetPosition, and UvwAsString().

Referenced by WriteUvw().

◆ UvwAsString()

static std::string casacore::UvwFile::UvwAsString ( const std::array< double, 3 > & uvw )

inlinestaticprivate

Definition at line 359 of file UvwFile.h.

Referenced by StoreOrCheck().

◆ WriteActiveBlock()

void casacore::UvwFile::WriteActiveBlock ( )

inlineprivate

Definition at line 311 of file UvwFile.h.

References active_block_, block_is_changed_, block_uvws_, file_, n_antennas_, reference_antenna_, and casacore::VarBufferedColumnarFile< BufferSize >::Write().

Referenced by ActivateBlock(), and Close().

◆ WriteHeader()

void casacore::UvwFile::WriteHeader ( )

inlineprivate

Definition at line 339 of file UvwFile.h.

References file_, kHeaderSize, kMagicHeaderTag, n_antennas_, reference_antenna_, rows_per_block_, and casacore::VarBufferedColumnarFile< BufferSize >::WriteHeader().

Referenced by Close(), and WriteUvw().

◆ WriteUvw()

void casacore::UvwFile::WriteUvw	(	uint64_t	row,
		size_t	antenna1,
		size_t	antenna2,
		const double *	uvw
	)

inline

Write a single row to the column.

This has to be done in a reasonable order; see the class description.

Parameters

row	denotes the row in the Casacore measurement set to be read.

The row/block is zero when there's not yet a full block written.

This baseline is the first baseline of a new block, so the block size can be determined

baseline = a2 - a1 with a1 = 0

baseline = a2 - a1 with a2 = 0

baseline = a2 - a1. Given a1: a2 = baseline + a1

baseline = a2 - a1. Given a2: a1 = a2 - baseline

Definition at line 116 of file UvwFile.h.

References ActivateBlock(), block_uvws_, file_, casacore::VarBufferedColumnarFile< BufferSize >::IsOpen(), IsSet(), kUnsetPosition, n_antennas_, n_rows_, reference_antenna_, rows_per_block_, start_antenna_2_, StoreOrCheck(), and WriteHeader().

Referenced by casacore::UvwStManColumn::putArrayV().

Member Data Documentation

◆ active_block_

uint64_t casacore::UvwFile::active_block_

private

Definition at line 397 of file UvwFile.h.

Referenced by ActivateBlock(), operator=(), ReadActiveBlock(), UvwFile(), and WriteActiveBlock().

◆ block_is_changed_

bool casacore::UvwFile::block_is_changed_

private

Definition at line 405 of file UvwFile.h.

Referenced by ActivateBlock(), Close(), operator=(), StoreOrCheck(), and WriteActiveBlock().

◆ block_uvws_

std::vector<std::array<double, 3> > casacore::UvwFile::block_uvws_

private

UVW for each antenna in the block.

Definition at line 404 of file UvwFile.h.

Referenced by Close(), IsSet(), operator=(), ReadActiveBlock(), ReadUvw(), StoreOrCheck(), UvwFile(), WriteActiveBlock(), and WriteUvw().

◆ file_

BufferedColumnarFile casacore::UvwFile::file_

private

Definition at line 377 of file UvwFile.h.

Referenced by Close(), Filename(), operator=(), ReadActiveBlock(), ReadHeader(), ReadUvw(), UvwFile(), WriteActiveBlock(), WriteHeader(), and WriteUvw().

◆ kHeaderSize

constexpr size_t casacore::UvwFile::kHeaderSize

staticconstexprprivate

The header: char[8] "Uvw-col\0" (=kMagicHeaderTag) uint64_t rows_per_block uint64_t reference_antenna uint64_t n_antenna.

Definition at line 372 of file UvwFile.h.

Referenced by ReadHeader(), and WriteHeader().

◆ kMagicHeaderTag

constexpr const char casacore::UvwFile::kMagicHeaderTag[8]

staticconstexprprivate

Definition at line 373 of file UvwFile.h.

Referenced by ReadHeader(), and WriteHeader().

◆ kUnsetPosition

constexpr std::array<double, 3> casacore::UvwFile::kUnsetPosition

staticconstexprprivate

Definition at line 374 of file UvwFile.h.

Referenced by IsSet(), ReadActiveBlock(), StoreOrCheck(), UvwFile(), and WriteUvw().

◆ n_antennas_

size_t casacore::UvwFile::n_antennas_

private

Definition at line 402 of file UvwFile.h.

Referenced by Close(), operator=(), ReadActiveBlock(), ReadHeader(), ReadUvw(), UvwFile(), WriteActiveBlock(), WriteHeader(), and WriteUvw().

◆ n_rows_

uint64_t casacore::UvwFile::n_rows_

private

Number of rows in the Uvw column.

It is increased when writing a new Uvw row using WriteUvw(). This concept of a "row" is different from a row in the BufferedColumnarFile (i.e., file_ ), as for each block (see below), only the uvw per antenna are stored, and these form the rows in that file.

Definition at line 385 of file UvwFile.h.

Referenced by Close(), NRows(), operator=(), ReadUvw(), UvwFile(), and WriteUvw().

◆ reference_antenna_

size_t casacore::UvwFile::reference_antenna_

private

Definition at line 398 of file UvwFile.h.

Referenced by operator=(), ReadActiveBlock(), ReadHeader(), UvwFile(), WriteActiveBlock(), WriteHeader(), and WriteUvw().

◆ rows_per_block_

uint64_t casacore::UvwFile::rows_per_block_

private

A "block" is a contiguous number of baselines that together form one timestep.

This is the same as saying they form one (triangular) correlation matrix. It can have auto-correlation but this is not required. A block may have missing antennas, but has some constraints on the ordering; see the class description. Per block, the UVW values are calculated per antenna. This value specifies the number of table rows in one block, i.e. the number of set elements in the correlation matrix.

Definition at line 396 of file UvwFile.h.

Referenced by Close(), operator=(), ReadHeader(), ReadUvw(), UvwFile(), WriteHeader(), and WriteUvw().

◆ start_antenna_2_

size_t casacore::UvwFile::start_antenna_2_

private

This value is used to determine the first baseline in the data, which is the baseline (reference_antenna_, start_antenna_2_).

Definition at line 401 of file UvwFile.h.

Referenced by operator=(), and WriteUvw().

The documentation for this class was generated from the following file:

tables/AlternateMans/UvwFile.h

Public Member Functions

Static Public Member Functions

Private Member Functions

Static Private Member Functions

Private Attributes

Static Private Attributes

Detailed Description

Constructor & Destructor Documentation

◆ UvwFile() [1/4]

◆ UvwFile() [2/4]

◆ ~UvwFile()

◆ UvwFile() [3/4]

◆ UvwFile() [4/4]

Member Function Documentation

◆ ActivateBlock()

◆ AreNear() [1/2]

◆ AreNear() [2/2]

◆ Close()

◆ CreateNew()

◆ Filename()

◆ IsSet()

◆ NRows()

◆ OpenExisting()

◆ operator=()

◆ ReadActiveBlock()

◆ ReadHeader()

◆ ReadUvw()

◆ StoreOrCheck()

◆ UvwAsString()

◆ WriteActiveBlock()

◆ WriteHeader()

◆ WriteUvw()

Member Data Documentation

◆ active_block_

◆ block_is_changed_

◆ block_uvws_

◆ file_

◆ kHeaderSize

◆ kMagicHeaderTag

◆ kUnsetPosition

◆ n_antennas_

◆ n_rows_

◆ reference_antenna_

◆ rows_per_block_

◆ start_antenna_2_