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");
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.
// 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);
Create the ROArrayMeasColumn from the table and column Name.
Copy constructor (copy semantics).
Change the reference to another column.
Attach a column to the object.
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.
Get the Measure array contained in the specified row and convert
it to the reference and offset found in the given measure.
Get the Measure array contained in the specified row and convert
it to the given reference.
Get the column's reference.
Assignment makes no sense in a read only class.
Declaring this operator private makes it unusable.
Deletes allocated memory etc. Called by ~tor and any member which needs
to reallocate data.
Get the data and convert using conversion engine.
Create the ROArrayMeasColumn from the table and column name.
Copy constructor (copy semantics).
Change the reference to another column.
Attach a column to the object.
Reset the refCode, offset, or units.
It overwrites the value used when defining the TableMeasDesc.
Resetting the refCode and offset can only be done if they were
defined as fixed in the description.
Add a Measure array to the specified row.
Declaring this operator private makes it unusable.
See class ArrayColumn for an
explanation as to why this operation is disallowed. Use the reference
function instead.
Deletes allocated memory etc. Called by ~tor and any member which needs
to reallocate data.
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
ROArrayMeasColumn& operator= (const ROArrayMeasColumn<M>& that)
void cleanUp()
Array<M> doConvert (uInt rownr, typename M::Convert& conv) const
template<class M> class ArrayMeasColumn : public ROArrayMeasColumn<M>
Interface
Description
Review Status
Synopsis
See description for
ROArrayMeasColumn.
Member Description
ArrayMeasColumn()
The default constructor creates a null object. Useful for creating
arrays of ROArrayMeasColumn objects. Attempting to use a null object
will produce a segmentation fault so care needs to be taken to
initialise the objects by using the attach() member before any attempt
is made to use the object. A ROArrayMeasColumn object can be tested
if it is null by using the isNull() member.
ArrayMeasColumn (const Table& tab, const String& columnName)
ArrayMeasColumn (const ArrayMeasColumn<M>& that)
virtual ~ArrayMeasColumn()
void reference (const ArrayMeasColumn<M>& that)
void attach (const Table& tab, const String& columnName)
void setDescRefCode (uInt refCode, Bool tableMustBeEmpty=True)
void setDescOffset (const Measure& offset, Bool tableMustBeEmpty=True)
void setDescUnits (const Vector<Unit>& units, Bool tableMustBeEmpty=True)
In principle the functions can only be used if the table is empty,
otherwise already written values have thereafter the incorrect
reference, offset, or unit.
However, it is possible that part of the table is already
written and that the entire measure column is filled in later.
In that case the reference, offset, or units can be set by using
a False tableMustBeEmpty argument.
void put (uInt rownr, const Array<M>&)
ArrayMeasColumn& operator= (const ArrayMeasColumn<M>& that)
void cleanUp()