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EleFits
5.0.0
A modern C++ API on top of CFITSIO
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#include <BintableColumns.h>
Column-wise reader-writer for the binary table data unit.
For flexibility, this handler class provides many methods to read and write data, but they are just different flavors of the following few services:
For reading, new columns can be either returned, or existing columns can be filled. Columns can be specified either by their name or index; using index is faster because names are internally converted to indices anyway, via a read operation. When filling an existing column, the name of the column can also be used to specify the column to be read.
When writing, if more rows are needed, they are automatically filled with zeros.
In the FITS file, binary tables are written row-wise, i.e. values of a row are contiguous in the file. As of today, in memory, values are stored column-wise (in Column) for convenience, to avoid heterogeneous containers as much as possible. This implies that read and write functions jump from one disk or memory adress to another all the time, which costs a lot of resources. To save on I/Os, an internal buffer is instantiated by CFITSIO. As opposed to methods to read and write a single column, methods to read and write several columns take advantage of the internal buffer. It is therefore much more efficient to use those than to chain several calls to methods for single columns. Depending on the table width, the speed-up can reach several orders of magnitude.
Method to read and write columns conform to the following naming convention:
read or write;Segment for reading or writing segments;Seq for reading or writing several columns;To for filling an existing column.For example, readSegmentSeqTo() is a method to read a sequence of segments into existing Column objects.
For working with segments, row indices are specified as Segments or FileMemSegments.
For example, assume we want to concatenate rows 11 to 50 of a 3-column binary table into some std::vector. Here is an option:
Public Member Functions | |
Column metadata. | |
| long | readColumnCount () const |
| Get the current number of columns. | |
| long | readRowCount () const |
| Get the current number of rows. | |
| long | readBufferRowCount () const |
| Get the number of rows in the internal buffer. More... | |
| bool | has (const std::string &name) const |
| Check whether the HDU contains a given column. More... | |
| long | readIndex (const std::string &name) const |
| Get the index of the column with given name. | |
| std::vector< long > | readIndices (const std::vector< std::string > &names) const |
| Get the indices of the columns with given names. | |
| std::string | readName (long index) const |
| Get the name of the column with given index. | |
| std::vector< std::string > | readAllNames () const |
| Get the names of all the columns. | |
| void | rename (ColumnKey key, const std::string &newName) const |
| Rename the column with given name or index. More... | |
Read a single column. | |
| template<typename T , long N = 1> | |
| ColumnInfo< T, N > | readInfo (ColumnKey key) const |
| Read the info of a column. More... | |
| template<typename T , long N = 1> | |
| VecColumn< T, N > | read (ColumnKey key) const |
| Read the column with given name or index. More... | |
| template<typename TColumn > | |
| void | readTo (TColumn &column) const |
Read a column into an existing Column. More... | |
| template<typename TColumn > | |
| void | readTo (ColumnKey key, TColumn &column) const |
Read the column with given name or index into an existing Column. More... | |
Read a single column segment. | |
| template<typename T , long N = 1> | |
| VecColumn< T, N > | readSegment (const Segment &rows, ColumnKey key) const |
| Read the segment of a column specified by its name or index. More... | |
| template<typename TColumn > | |
| void | readSegmentTo (FileMemSegments rows, TColumn &column) const |
Read the segment of a column into an existing Column. More... | |
| template<typename TColumn > | |
| void | readSegmentTo (FileMemSegments rows, ColumnKey key, TColumn &column) const |
Read the segment of a column specified by its name or index into an existing Column. More... | |
Read a sequence of columns. | |
| template<typename TKey , typename... Ts> | |
| std::tuple< VecColumn< Ts, 1 >... > | readSeq (const TypedKey< Ts, TKey > &... keys) const |
| Read a tuple of columns with given names or indices. More... | |
| template<typename T , long N = 1> | |
| std::vector< VecColumn< T, N > > | readSeq (std::vector< ColumnKey > keys) const |
| Read a vector of columns with given names or indices. More... | |
| template<typename TSeq > | |
| void | readSeqTo (TSeq &&columns) const |
Read a sequence of columns into existing Columns. More... | |
| template<typename... TColumns> | |
| void | readSeqTo (TColumns &... columns) const |
Read a sequence of columns into existing Columns. More... | |
| template<typename TSeq > | |
| void | readSeqTo (std::vector< ColumnKey > keys, TSeq &&columns) const |
Read a sequence of columns with given names or indices into existing Columns. More... | |
| template<typename... TColumns> | |
| void | readSeqTo (std::vector< ColumnKey > keys, TColumns &... columns) const |
Read a sequence of columns with given names or indices into existing Columns. More... | |
Read a sequence of column segments. | |
| template<typename TKey , typename... Ts> | |
| std::tuple< VecColumn< Ts, 1 >... > | readSegmentSeq (Segment rows, const TypedKey< Ts, TKey > &... keys) const |
| Read segments of columns specified by their names or indices. More... | |
| template<typename T , long N = 1> | |
| std::vector< VecColumn< T, N > > | readSegmentSeq (Segment rows, std::vector< ColumnKey > keys) const |
| Read segments of columns specified by their names or indices. More... | |
| template<typename TSeq > | |
| void | readSegmentSeqTo (FileMemSegments rows, TSeq &&columns) const |
Read segments of columns into existing Columns. More... | |
| template<typename... TColumns> | |
| void | readSegmentSeqTo (FileMemSegments rows, TColumns &... columns) const |
Read segments of columns into existing Columns. More... | |
| template<typename TSeq > | |
| void | readSegmentSeqTo (FileMemSegments rows, std::vector< ColumnKey > keys, TSeq &&columns) const |
Read segments of columns specified by their names or indices into existing Columns. More... | |
| template<typename... TColumns> | |
| void | readSegmentSeqTo (FileMemSegments rows, std::vector< ColumnKey > keys, TColumns &... columns) const |
Read segments of columns specified by their names or indices into existing Columns. More... | |
Write a single column. | |
| template<typename TColumn > | |
| void | write (const TColumn &column) const |
| Write a column. | |
| template<typename TInfo > | |
| void | init (const TInfo &info, long index=-1) const |
| Append or insert a column, which was not previously initialized. More... | |
| void | remove (ColumnKey key) const |
| Remove a column specified by its name or index. | |
Write a single column segment. | |
| template<typename TColumn > | |
| void | writeSegment (FileMemSegments rows, const TColumn &column) const |
| Write a column segment. More... | |
Write a sequence of columns. | |
| template<typename TSeq > | |
| void | writeSeq (TSeq &&columns) const |
| Write several columns. | |
| template<typename... TColumns> | |
| void | writeSeq (const TColumns &... columns) const |
| Write several columns. More... | |
| template<typename TSeq > | |
| void | initSeq (long index, TSeq &&infos) const |
| Append or insert a sequence of columns, which were not previously initialized. More... | |
| template<typename... TInfos> | |
| void | initSeq (long index, const TInfos &... infos) const |
| Append or insert a sequence of columns, which were not previously initialized. More... | |
| void | removeSeq (std::vector< ColumnKey > keys) const |
| Remove a sequence of columns specified by their names or indices. | |
Write a sequence of column segments. | |
| template<typename TSeq > | |
| void | writeSegmentSeq (FileMemSegments rows, TSeq &&columns) const |
| Write a sequence of segments. More... | |
| template<typename... TColumns> | |
| void | writeSegmentSeq (FileMemSegments rows, const TColumns &... columns) const |
| Write a sequence of segments. More... | |