casa::ArrayPartMath_global_functions_Array_partial_operations Struct Reference [Arrays_module]

Mathematical and logical operations for Array parts. More...

#include <ArrayPartMath.h>

List of all members.

Classes
class	AvdevFunc
class	FractileFunc
class	MaxFunc
class	MeanFunc
class	MedianFunc
class	MinFunc
class	ProductFunc
class	RmsFunc
class	StddevFunc
class	SumFunc
class	VarianceFunc
Public Member Functions
template<class T >
Array< T >	partialSums (const Array< T > &array, const IPosition &collapseAxes)
	Determine the sum, product, etc.
template<class T >
Array< T >	partialProducts (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialMins (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialMaxs (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialMeans (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialVariances (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialVariances (const Array< T > &array, const IPosition &collapseAxes, const Array< T > &means)
template<class T >
Array< T >	partialStddevs (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialStddevs (const Array< T > &array, const IPosition &collapseAxes, const Array< T > &means)
template<class T >
Array< T >	partialAvdevs (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialAvdevs (const Array< T > &array, const IPosition &collapseAxes, const Array< T > &means)
template<class T >
Array< T >	partialRmss (const Array< T > &array, const IPosition &collapseAxes)
template<class T >
Array< T >	partialMedians (const Array< T > &array, const IPosition &collapseAxes, Bool takeEvenMean=False, Bool inPlace=False)
template<class T >
Array< T >	partialFractiles (const Array< T > &array, const IPosition &collapseAxes, Float fraction, Bool inPlace=False)
template<typename T , typename FuncType >
Array< T >	boxedArrayMath (const Array< T > &array, const IPosition &boxSize, const FuncType &funcObj)
	Apply the given ArrayMath reduction function objects to each box in the array.
template<typename T , typename FuncType >
Array< T >	slidingArrayMath (const Array< T > &array, const IPosition &halfBoxSize, const FuncType &funcObj, Bool fillEdge=True)
	Apply for each element in the array the given ArrayMath reduction function object to the box around that element.

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Detailed Description

Mathematical and logical operations for Array parts.

Review Status

Reviewed By:

UNKNOWN

Date Reviewed:

before2004/08/25

Test programs:

tArray

Prerequisite

• Array

Etymology

This file contains global functions which perform part by part mathematical or logical operations on arrays.

Synopsis

These functions perform chunk by chunk mathematical operations on arrays. In particular boxed and sliding operations are possible. E.g. to calculate the median in sliding windows making it possible to subtract the background in an image.

The operations to be performed are defined by means of functors that reduce an array subset to a scalar. Those functors are wrappers for ArrayMath and ArrayLogical functions like sum, median, and ntrue.

The partialXX functions are a special case of the BoxedArrayMath function. They reduce one or more entire axes which can be done in a faster way than the more general boxedArrayMath function.

Example

    Array<Double> data(...);
    Array<Double> means = partialMeans (data, IPosition(2,0,1));

This example calculates the mean of each plane in the data array.

Example

    IPosition shp = data.shape();
    Array<Double> means = boxedArrayMath (data, IPosition(2,shp[0],shp[1]),
                                          SumFunc<Double>());

does the same as the first example. Note that in this example the box is formed by the entire axes, but it could also be a subset of it to average, say, boxes of 5*5 elements.

Definition at line 91 of file ArrayPartMath.h.

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Member Function Documentation

template<typename T , typename FuncType >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::boxedArrayMath	(	const Array< T > &	array,
		const IPosition &	boxSize,
		const FuncType &	funcObj
	)

Apply the given ArrayMath reduction function objects to each box in the array.

Example

Downsample an array by taking the median of every [25,25] elements.

       Array<Float> downArr = boxedArrayMath(in, IPosition(2,25,25),
                                             MedianFunc<Float>());

The dimensionality of the array can be larger than the box; in that case the missing axes of the box are assumed to have length 1. A box axis length <= 0 means the full array axis.

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialAvdevs	(	const Array< T > &	array,
		const IPosition &	collapseAxes,
		const Array< T > &	means
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialAvdevs	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)			[inline]

Definition at line 136 of file ArrayPartMath.h.

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialFractiles	(	const Array< T > &	array,
		const IPosition &	collapseAxes,
		Float	fraction,
		Bool	inPlace = False
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialMaxs	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialMeans	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialMedians	(	const Array< T > &	array,
		const IPosition &	collapseAxes,
		Bool	takeEvenMean = False,
		Bool	inPlace = False
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialMins	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialProducts	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialRmss	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialStddevs	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)			[inline]

Definition at line 124 of file ArrayPartMath.h.

References casa::sqrt().

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialStddevs	(	const Array< T > &	array,
		const IPosition &	collapseAxes,
		const Array< T > &	means
	)			[inline]

Definition at line 130 of file ArrayPartMath.h.

References casa::sqrt().

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialSums	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)

Determine the sum, product, etc.

for the given axes only. The result is an array with a shape formed by the remaining axes. For example, for an array with shape [3,4,5], collapsing axis 0 results in an array with shape [4,5] containing, say, the sum for each X line. Summing for axes 0 and 2 results in an array with shape [4] containing, say, the sum for each XZ plane.
Note: ArrayLogical;h contains the functions ntrue, nfalse, partialNTrue and partialNFalse to count the number of true or false elements in an array;

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialVariances	(	const Array< T > &	array,
		const IPosition &	collapseAxes,
		const Array< T > &	means
	)

template<class T >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::partialVariances	(	const Array< T > &	array,
		const IPosition &	collapseAxes
	)			[inline]

Definition at line 115 of file ArrayPartMath.h.

template<typename T , typename FuncType >

Array<T> casa::ArrayPartMath_global_functions_Array_partial_operations::slidingArrayMath	(	const Array< T > &	array,
		const IPosition &	halfBoxSize,
		const FuncType &	funcObj,
		Bool	fillEdge = True
	)

Apply for each element in the array the given ArrayMath reduction function object to the box around that element.

The full box is 2*halfBoxSize + 1. It can be used for arrays and boxes of any dimensionality; missing halfBoxSize values are set to 1.

Example

Determine for each element in the array the median of a box with size [51,51] around that element:

       Array<Float> medians = slidingArrayMath(in, IPosition(2,25,25),
                                               MedianFunc<Float>());

This is a potentially expensive operation. On a high-end PC it took appr. 27 seconds to get the medians for an array of [1000,1000] using a halfBoxSize of [50,50].

The fillEdge argument determines how the edge is filled where no full boxes can be made. True means it is set to zero; False means that the edge is removed, thus the output array is smaller than the input array.
Note: This brute-force method of determining the medians outperforms all kinds of smart implementations; For a vector it is about as fast as class MedianSlider , for a 2D array it is much, much faster;

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The documentation for this struct was generated from the following file:

• casa/Arrays/ArrayPartMath.h