A MaskedArray should be thought of as a manipulator for an Array, analogous to an iterator. It allows one to perform whole Array operations on selected elements of the Array.
The mask used in the constructor for the MaskedArray must conform to the Array, thus have the same shape. The internal mask is (will be) copy constructed with reference semantics from the input mask. Therefore, it is (will be) possible to change the internal mask by changing values in the input mask *after* the MaskedArray has been constructed. To ensure that the internal mask is independent of the input mask after construction, use mask.copy() as the input argument.
One can explicitly construct a MaskedArray from an Array and a mask or a MaskedArray and a mask. One can also use operator() on an Array or a MaskedArray to implicitly create a MaskedArray.
One can create a MaskedArray from a MaskedArray and a mask. The resulting MaskedArray has as its Array the Array from the original MaskedArray. The mask for the resulting MaskedArray is the AND of the mask from the original MaskedArray and the input mask.
Any operation involving a MaskedArray or a set of MaskedArrays is only performed for those elements where the AND of the masks is True.
Any operation involving a MaskedArray or a set of MaskedArrays results in a MaskedArray whose mask is the AND of the masks of the original MaskedArrays. The only exception to this is assignment, where the mask determines which elements of the underlying Array are assigned.
Masks, which are LogicalArrays, can be constructed by logical operations involving Arrays. They can also, of course, be constructed by individually setting individual elements of an LogicalArray.
MaskedArrays constructed directly from Arrays are by default writeable. MaskedArrays constructed indirectly from Arrays by operator() are writeable if the Array is non-const and are readonly if the Array is const. MaskedArrays constructed from other MaskedArrays, either directly by constructors or indirectly by operator(), are by default writeable if the input MaskedArray is writeable, and readonly if the input MaskedArray is readonly.
A given MaskedArray can be set to be readonly. One specifies this in the constructor with the Bool argument isreadonly, or calls the setReadOnly() member function. A MaskedArray which would default to be readonly cannot be forced to be writeable. It will remain readonly even if the Bool argument isreadonly is set to be False.
The isReadOnly(), member function is used to test whether the MaskedArray is readonly.
Member functions which change the MaskedArray test to see whether the MaskedArray is readonly, and throw an ArrayError exception if it is. These member functions are:
The copy() member function makes a deep copy of a MaskedArray. By default it returns a writeable MaskedArray, but the MaskedArray returned can be made readonly by using the Bool argument "isreadonly" to copy() (or by calling setReadOnly() on the new MaskedArray).
The valid elements of the MaskedArray can be manipulated as a "compressed" Array which contains only the valid elements. The number of elements in this "compressed" Array is the number of valid elements in the MaskedArray, nelementsValid(). The "compressed" Array can have any shape which meets this requirement. The MaskedArray can have any shape.
The getCompressedArray() member functions get a compressed Array from the valid members of the MaskedArray, while the setCompressedArray() member function sets the valid members of the MaskedArray from the input compressed Array.
Many mathematical and logical global operators and functions which operate on MaskedArrays are defined. Typically, they are defined for all sensible combinations of MaskedArrays, Arrays, and scalars.
Mathematical global operators and functions are defined in Arrays/MaskArrMath.h . The list is:
Logical global operators and functions are defined in Arrays/MaskArrLogi.h . The list is:
Vector<Int> arr (20);
. . .
MaskedArray<Int> marr (arr, (arr > 5));
marr = 5;
This sets all elements of arr which are greater than 5 to 5.
Vector<Int> arr (20);
. . .
arr (arr < 0) = 0;
This sets all elements of arr which are less than 0 to 0.
The following expressions are all equivalent. The first (and second) expressions are the most efficient, since the sum is only performed for those elements where ((a > 0) && (b > 0)). The third example is less efficient, since the sum is performed for all elements of a and b, and then the assignment is only performed for those elements where ((a > 0) && (b > 0)).
Vector<Int> arr (20);
Vector<Int> a (20);
Vector<Int> b (20);
. . .
arr = a(a > 0) + b(b > 0);
arr = a(b > 0) + b(a > 0);
arr ((a > 0) && (b > 0)) = a + b;
arr = (a + b) ((a > 0) && (b > 0));
arr (a > 0) = a + b(b > 0);
All of these expressions set those elements of arr where ((a > 0) && (b > 0)) to a + b. Those elements of arr where the condition is False are unchanged.
Matrix<Int> arr (20,5);
. . .
MaskedArray<Int> marr (arr, (arr>0) && (arr<10));
Vector<Int> vec (marr.getCompressedArray());
. . .
marr.setCompressedArray (vec);
The internal mask is a total copy of the input mask, and is completely independent of the input mask.
The Array is copy constructed, which means that it is a really smart pointer to the underlying Block, and shares this Block with the input Array.
By default, the MaskedArray constructed is writeable. If isreadonly is True, then the MaskedArray returned is readonly.
Create a MaskedArray from a MaskedArray and a LogicalArray.
The internal mask is the AND of the input mask and the mask of the input MaskedArray.
The Array from the input MaskedArray is copy constructed, which means that it is a really smart pointer to the underlying Block, and shares this Block with the Array from the input MaskedArray.
By default, the MaskedArray constructed is writeable if the input MaskedArray is writeable, and readonly if the input MaskedArray is readonly. If isreadonly is True, then the MaskedArray returned is readonly. If isreadonly is False and the input MaskedArray is readonly, then the constructed MaskedArray is readonly.
Create a MaskedArray from an Array and a MaskedLogicalArray.
The internal mask is the AND of the internal LogicalArray and the internal mask of the MaskedLogicalArray.
The Array is copy constructed, which means that it is a really smart pointer to the underlying Block, and shares this Block with the input Array.
By default, the MaskedArray constructed is writeable. If isreadonly is True, then the MaskedArray returned is readonly.
Create a MaskedArray from a MaskedArray and a MaskedLogicalArray.
The internal mask is the AND of the internal LogicalArray and the internal mask of the MaskedLogicalArray, ANDed with the mask of the input MaskedArray.
The Array from the input MaskedArray is copy constructed, which means that it is a really smart pointer to the underlying Block, and shares this Block with the Array from the input MaskedArray.
By default, the MaskedArray constructed is writeable if the input MaskedArray is writeable, and readonly if the input MaskedArray is readonly. If isreadonly is True, then the MaskedArray returned is readonly. If isreadonly is False and the input MaskedArray is readonly, then the constructed MaskedArray is readonly.
Copy constructor.
The internal mask is a total copy of the mask from the input MaskedArray, and is completely independent of this input mask.
The Array from the input MaskedArray is copy constructed, which means that it is a really smart pointer to the underlying Block, and shares this Block with the Array from the input MaskedArray.
By default, the MaskedArray constructed is writeable if the input MaskedArray is writeable, and readonly if the input MaskedArray is readonly. If isreadonly is True, then the MaskedArray returned is readonly. If isreadonly is False and the input MaskedArray is readonly, then the constructed MaskedArray is readonly.
Return a MaskedArray. The new MaskedArray is masked by the input LogicalArray "anded" with the mask of the original MaskedArray. This mask must conform to the array.
The MaskedArray constructed is writeable if the input MaskedArray is writeable, and readonly if the input MaskedArray is readonly.
Return a MaskedArray. The new MaskedArray is masked by the input MaskedLogicalArray "anded" with the mask of the original MaskedArray. This mask must conform to the array.
The MaskedArray constructed is writeable if the input MaskedArray is writeable, and readonly if the input MaskedArray is readonly.
Make a copy of the masked array.
This is a deep copy. The Array and mask components of the returned MaskedArray are deep copies of the Array and mask in the input MaskedArray pointed to by this. In other words, the Array and mask in the output MaskedArray are completely independent of those in the input MaskedArray.
By default, the MaskedArray returned is writeable. If isreadonly is True, then the MaskedArray returned is readonly.
Return the internal Array.
Return the internal Array, writeable.
Return the (const) internal Mask.
The dimensionality of this masked array.
The number of elements of this masked array. This is the number of elements in the underlying Array.
The number of valid elements of this masked array. This is the number of elements of the mask which are TRUE.
Check to see if the masked array is consistent. This is about the same thing as checking for invariants. If AIPS_DEBUG is defined, this is invoked after construction and on entry to most member functions.
Are the shapes identical?
The length of each axis.
Is the array read only?
Set the array to be read only.
Copy the values in inarray to this, only copying those elements for which the corresponding mask element is True.
Copy the values in other to this, only copying those elements for which the logical AND of the corresponding mask elements of both MaskedArrays is True.
Set every element of this array to "value", only setting those elements for which the corresponding mask element is True. In other words, a scalar behaves as if it were a constant conformant array.
Return a "compressed" Array containing only the valid elements of the MaskedArray. The number of elements in the Array will be nelementsValid() for the MaskedArray. The MaskedArray can have any shape.
The returned Array will have dimension one.
Return a "compressed" Array containing only the valid elements of the MaskedArray. The number of elements in the Array will be nelementsValid() for the MaskedArray. The MaskedArray can have any shape.
The returned Array will have the input shape. This shape must give the returned Array the required number of elements.
Fill the argument "compressed" Array with only the valid elements of the MaskedArray. The size of the Array must be nelementsValid() for the MaskedArray. The Array can have any shape which meets this requirement. The MaskedArray can have any shape.
Set only the valid elements of the MaskedArray from the argument "compressed" Array. The size of the Array must be nelementsValid() for the MaskedArray. The Array can have any shape which meets this requirement. The MaskedArray can have any shape.
Manipulate the storage for the underlying Array. See the description of the corresponding Array functions for more information.
Manipulate the storage for the underlying Array. See the description of the corresponding Array functions for more information.
Manipulate the storage for the underlying Array. See the description of the corresponding Array functions for more information.
Manipulate the storage for the underlying Mask. See the description of the corresponding Array functions for more information.
Test conformance for masked arrays and arrays of different types. Are the shapes identical?