ArrayLattice.h

Classes

ArrayLattice -- A memory resident Lattice (full description)

template <class T> class ArrayLattice : public Lattice<T>

Interface

Public Members
ArrayLattice()
explicit ArrayLattice (const IPosition& shape)
ArrayLattice (Array<T>& array, Bool isWritable = True)
ArrayLattice (const Array<T>& array)
ArrayLattice (const ArrayLattice<T>& other)
~ArrayLattice()
ArrayLattice<T>& operator= (const ArrayLattice<T>& other)
virtual Lattice<T>* clone() const
virtual Bool canReferenceArray() const
virtual Bool isWritable() const
virtual IPosition shape() const
virtual void set (const T& value)
Array<T>& asArray()
const Array<T>& asArray() const
virtual T getAt (const IPosition& where) const
virtual void putAt (const T& value, const IPosition& where)
virtual Bool ok() const
virtual uInt advisedMaxPixels() const
void getIterSlice (Array<T>& buffer, const IPosition& start, const IPosition& end, const IPosition& incr)
Protected Members
virtual Bool doGetSlice (Array<T>& buffer, const Slicer& section)
virtual void doPutSlice (const Array<T>& sourceBuffer, const IPosition& where, const IPosition& stride)
See Also
PagedArray - a disk based Lattice.

Description

Review Status

Reviewed By:
Peter Barnes
Date Reviewed:
1999/10/30
Programs:
Tests:

Prerequisite

Etymology

The ArrayLattice name reflects its role as a Lattice interface to an Array object.

Synopsis

An ArrayLattice is a concrete Lattice class where the data is stored in memory as opposed to the PagedArray class where the data is stored on disk. As a result this class is much more suitable to problems which require small Lattices that can fit into the memory of a computer.

ArrayLattice imposes another layer of function calls on top of a an Array. As a result they should not be used for generic Array manipulation. They are useful if you have an Array that needs to use Lattice functions or needs to be used with PagedArrays or other Lattice derivatives (like LatticeExpr or SubLattice). For example the LatticeIterator class can iterate through an Array in more ways than any of the ArrayIterator classes can. The examples below illustrate some uses for ArrayLattices.

Example

All the examples in this section are available in dArrayLattice.cc

Example 1:

In this example an Array of data is converted into an ArrayLattice so that the copyData function can be used to write the data to a PagedArray which will be stored on disk.
    // make an Array and fill it with data.
    Array<Float> myArray(IPosition(3, 64, 64, 2));
    indgen(myArray); // fills the Array with 0,1,2,....,64*64*2-1
    // construct the ArrayLattice
    ArrayLattice<Float> myLattice(myArray);
    // make a PagedArray to store the data on disk
    PagedArray<Float> myPagedArray(myLattice.shape(), "myTestData.array");
    // now copy the data onto disk
    myPagedArray.copyData (myLattice);
    
Note that it could be done in a somewhat simpler way as:
    // make an Array and fill it with data.
    Array<Float> myArray(IPosition(3, 64, 64, 2));
    indgen(myArray); // fills the Array with 0,1,2,....,64*64*2-1
    // make a PagedArray to store the data on disk
    PagedArray<Float> myPagedArray(myLattice.shape(), "myTestData.array");
    // now put the data onto disk
    myPagedArray.put (myArray);
    

Example 2:

The ArrayIterator class (or its derivatives the VectorIterator and the MatrixIterator classes) do not allow the user to specify a cursor shape. In this example a Cube class will be converted into an ArrayLattice so that an ArrLatticeIter can be used to access the data spectrum by spectrum (assuming the z-axis is frequency).

    Cube<Float> arr(64,64,128);
    // assume that the data gets put into the cube somehow
    // now construct an ArrayLattice from this cube.
    ArrayLattice<Float> lat(arr);
    // Construct an iterator that returns the 128-element spectra one at a time
    ArrLatticeIter<Float> iter(lat, IPosition(3,1,1,128));
    // construct a Matrix to hold the results
    Matrix<Float> channelSum(64,64);
    // and do the summation one spectrum at a time
    for (iter.reset(); !iter.atEnd(); iter++)
       channelSum(iter.position().getFirst(2)) = sum(iter.cursor());
    

There are more examples in the Lattice class and many of the examples in the PagedArray class will also be instructive.

Motivation

We needed a way of creating Lattices but with AIPS++ Array characteristics.

Member Description

ArrayLattice()

The default constructor creates a ArrayLattice that is useless for just about everything, except that it can be assigned to with the assignment operator.

explicit ArrayLattice (const IPosition& shape)

Construct an ArrayLattice with the specified shape. It results in a writable lattice.

ArrayLattice (Array<T>& array, Bool isWritable = True)

Construct an ArrayLattice that references the given Array. By default it results in a writable lattice.

ArrayLattice (const Array<T>& array)

Construct an ArrayLattice that references the given Array. It results in a non-writable lattice.

ArrayLattice (const ArrayLattice<T>& other)

The copy constructor uses reference semantics.

~ArrayLattice()

ArrayLattice<T>& operator= (const ArrayLattice<T>& other)

The assignment operator uses copy semantics.

virtual Lattice<T>* clone() const

Make a copy of the object (reference semantics).

virtual Bool canReferenceArray() const

The lattice data can be referenced as an array section.

virtual Bool isWritable() const

Is the lattice writable?

virtual IPosition shape() const

returns the shape of the ArrayLattice.

virtual void set (const T& value)

Set all of the elements in the Lattice to a value.

Array<T>& asArray()
const Array<T>& asArray() const

Return the Array of the data within this Lattice.

virtual T getAt (const IPosition& where) const

Return the value of the single element located at the argument IPosition. Note that operator() (defined in the base class) can also be used.

virtual void putAt (const T& value, const IPosition& where)

Put the value of a single element.

virtual Bool ok() const

Check for internal consistency. Returns False if something nasty has happened to the ArrayLattice.

virtual uInt advisedMaxPixels() const

Returns the maximum recommended number of pixels for a cursor. For this class this is equal to the number of pixels in the lattice.

void getIterSlice (Array<T>& buffer, const IPosition& start, const IPosition& end, const IPosition& incr)

Get a slice in an optimized way (specifically for ArrLatticeIter). It returns in buffer a reference to the lattice array.

virtual Bool doGetSlice (Array<T>& buffer, const Slicer& section)

Do the actual getting of an array of values.

virtual void doPutSlice (const Array<T>& sourceBuffer, const IPosition& where, const IPosition& stride)

Do the actual putting of an array of values.