ArrayMeasColumn.h

Classes

ROArrayMeasColumn -- Read only access to table array Measure columns. (full description)

ArrayMeasColumn -- Read write access to table array Measure columns. (full description)

template<class M> class ROArrayMeasColumn : public ROTableMeasColumn

Interface

Public Members

ROArrayMeasColumn()

ROArrayMeasColumn (const Table& tab, const String& columnName)

ROArrayMeasColumn (const ROArrayMeasColumn<M>& that)

virtual ~ROArrayMeasColumn()

void reference (const ROArrayMeasColumn<M>& that)

void attach (const Table& tab, const String& columnName)

void get (uInt rownr, Array<M>& meas, Bool resize = False) const

Array<M> operator() (uInt rownr) const

Array<M> convert (uInt rownr, const M& meas) const

Array<M> convert (uInt rownr, const MeasRef<M>& measRef) const

Array<M> convert (uInt rownr, uInt refCode) const

const MeasRef<M>& getMeasRef() const

Private Members

ROArrayMeasColumn& operator= (const ROArrayMeasColumn<M>& that)

void cleanUp()

Array<M> doConvert (uInt rownr, typename M::Convert& conv) const

Description

Review Status

Reviewed By:

Bob Garwood

Date Reviewed:

1999/12/23

Programs:

Tests:

• tTableMeasures.cc

Prerequisite

• Measures
• Tables
• TableMeasDesc

Synopsis

Before a column can be accessed it must have previously been defined as a Measure column by use of the TableMeasDesc object.

The (RO)ArrayMeasColumn class is templated on Measure type and MeasValue type but typedefs exist for making declaration less long winded. The Measure classes (like MEpoch) have typedefs ROArrayColumn and ArrayColumn to assist in creating (RO)ArrayMeasColumn objects.

Constructing array Measure column objects using these typedefs looks like this:

    // Read/write MEpoch array column
    MEpoch::ArrayColumn ec(table, "ColumnName);
    // Readonly MDoppler array column
    MDoppler::ROArrayColumn dc(table, "DopplerCol");
    

Reading and writing Measures

The reading and writing of Measures columns is very similar to reading and writing of "ordinary" Table columns. get() and operator() exist for reading Measures and the put() member for adding Measures to a column. (put() is obviously not defined for ROScalarMeasColumn objects.) Each of these members accepts a row number as an argument.

Care needs to be taken when adding Measures to a column. The user needs to be aware that Measures are not checked for consistency, with respect to a Measure's reference, between the Measures being added to a column and the column's predefined Measure reference. This is only an issue if the Measure column was defined to have a fixed reference. For such columns the reference component of Measures added to a column is silently ignored, that is, there is no warning nor is there any sort of conversion to the column's reference should the reference of the added Measure be different from the column's reference. The members isRefVariable() and getMeasRef() can be used to discover a Measure column's Measure reference characteristics.

Example

    // create an MEpoch array column object
    MEpochArrCol arrayCol;

    // should be null.  Can test this and attach a real MEpoch column
    // The column Time1Arr should exist in the table and would have been
    // defined by using a TableMeasDesc
    if (arrayCol.isNull()) {
	    arrayCol.attach(tab, "Time1Arr");
    }

    // This would throw an Exception if the object is still null....but
    // hopefully won't
    arrayCol.throwIfNull();

    // create a vector of MEpochs
    MEpoch last(Quantity(13.45, "h"), MEpoch::Ref(MEpoch::TAI));
    Vector<MEpoch> ev(10);
    for (uInt i=0; i<10; i++) {
        last.set(Quantity(13.45 + i, "h"));
        ev(i) = last;
    }

    // before adding something check the isDefined() member
    if (!arrayCol.isDefined(0)) {
        cout << "PASS - nothing in the measure array column row yet\n";
    } else {
        cout << "FAIL - there shouldn't be a valid value in the row!\n";
    }

    // add the MEpoch vector to the array Measure column at row 0
    arrayCol.put(0, ev);

    // now read the array from the row.  Could use same object to do this
    // but here we'll create a ROMEpochArrCol to do this
    ROMEpochArrCol roArrCol(tab, "Time1Arr");

    // need a vector to put the MEpochs into
    Vector<MEpoch> ew;

    // setting the resize parameter to True automatically sets ew to the
    // same shape as the array contained in the row
    arrayCol.get(0, ew, True);

Motivation

Thrown Exceptions

• ArrayConformanceError during get() if supplied array is the wrong shape.

Member Description

ROArrayMeasColumn()

ROArrayMeasColumn (const Table& tab, const String& columnName)

Create the ROArrayMeasColumn from the table and column Name.

ROArrayMeasColumn (const ROArrayMeasColumn<M>& that)

Copy constructor (copy semantics).

virtual ~ROArrayMeasColumn()

void reference (const ROArrayMeasColumn<M>& that)

Change the reference to another column.

void attach (const Table& tab, const String& columnName)

Attach a column to the object.

void get (uInt rownr, Array<M>& meas, Bool resize = False) const
Array<M> operator() (uInt rownr) const

Get the Measure array in the specified row. For get() the supplied array's shape should match the shape in the row unless resize is True.

Array<M> convert (uInt rownr, const M& meas) const

Get the Measure array contained in the specified row and convert it to the reference and offset found in the given measure.

Array<M> convert (uInt rownr, const MeasRef<M>& measRef) const
Array<M> convert (uInt rownr, uInt refCode) const

Get the Measure array contained in the specified row and convert it to the given reference.

const MeasRef<M>& getMeasRef() const

Get the column's reference.

ROArrayMeasColumn& operator= (const ROArrayMeasColumn<M>& that)

Assignment makes no sense in a read only class. Declaring this operator private makes it unusable.

void cleanUp()

Deletes allocated memory etc. Called by ~tor and any member which needs to reallocate data.

Array<M> doConvert (uInt rownr, typename M::Convert& conv) const

Get the data and convert using conversion engine.

template<class M> class ArrayMeasColumn : public ROArrayMeasColumn<M>

Interface