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/*-
*
* * Copyright 2015 Skymind,Inc.
* *
* * Licensed under the Apache License, Version 2.0 (the "License");
* * you may not use this file except in compliance with the License.
* * You may obtain a copy of the License at
* *
* * http://www.apache.org/licenses/LICENSE-2.0
* *
* * Unless required by applicable law or agreed to in writing, software
* * distributed under the License is distributed on an "AS IS" BASIS,
* * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* * See the License for the specific language governing permissions and
* * limitations under the License.
*
*
*/
package org.nd4j.linalg.fft;
import org.nd4j.linalg.api.complex.IComplexNDArray;
import org.nd4j.linalg.api.ndarray.INDArray;
import org.nd4j.linalg.api.ops.impl.transforms.VectorFFT;
import org.nd4j.linalg.factory.Nd4j;
import org.nd4j.linalg.util.ArrayUtil;
import org.nd4j.linalg.util.ComplexNDArrayUtil;
/**
* Abstract FFT Instance mostly handling basic things that shouldn't change
* such as method overloading.
*
* @author Adam Gibson
*/
public abstract class BaseFFTInstance implements FFTInstance {
/**
* FFT along a particular dimension
*
* @param transform the ndarray to op
* @param numElements the desired number of elements in each fft
* @return the ffted output
*/
@Override
public IComplexNDArray fft(INDArray transform, int numElements) {
IComplexNDArray inputC = Nd4j.createComplex(transform);
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(new VectorFFT(inputC, inputC.length()));
else {
return rawfft(inputC, numElements, inputC.shape().length - 1);
}
}
/**
* 1d discrete fourier op, note that this will
* throw an exception if the passed in input
* isn't a vector.
* See matlab's fft2 for more information
*
* @param inputC the input to op
* @return the the discrete fourier op of the passed in input
*/
@Override
public IComplexNDArray fft(IComplexNDArray inputC) {
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(new VectorFFT(inputC, inputC.length()));
else {
return rawfft(inputC, inputC.size(inputC.shape().length - 1), inputC.shape().length - 1);
}
}
/**
* 1d discrete fourier op, note that this will
* throw an exception if the passed in input
* isn't a vector.
* See matlab's fft2 for more information
*
* @param input the input to op
* @return the the discrete fourier op of the passed in input
*/
@Override
public IComplexNDArray fft(INDArray input) {
IComplexNDArray inputC = Nd4j.createComplex(input);
return fft(inputC);
}
/**
* 1d discrete fourier op, note that this will
* throw an exception if the passed in input
* isn't a vector.
* See matlab's fft2 for more information
*
* @param inputC the input to op
* @return the the discrete fourier op of the passed in input
*/
@Override
public IComplexNDArray fft(IComplexNDArray inputC, int numElements) {
return fft(inputC, numElements, inputC.shape().length - 1);
}
/**
* ND IFFT, computes along the first on singleton dimension of
* op
*
* @param transform the ndarray to op
* @param dimension the dimension to iterate along
* @param numElements the desired number of elements in each fft
* @return the reverse ifft of the passed in array
*/
@Override
public IComplexNDArray ifftn(INDArray transform, int dimension, int numElements) {
return ifftn(Nd4j.createComplex(transform), dimension, numElements);
}
@Override
public IComplexNDArray irfftn(IComplexNDArray arr) {
int[] shape = arr.shape();
IComplexNDArray ret = arr.dup();
for (int i = 0; i < shape.length - 1; i++) {
ret = ifftn(ret, i, shape[i]);
}
return irfft(ret, 0);
}
@Override
public IComplexNDArray irfft(IComplexNDArray arr, int dimension) {
return fftn(arr, arr.size(dimension), dimension);
}
@Override
public IComplexNDArray irfft(IComplexNDArray arr) {
return arr;
}
/**
* ND IFFT
*
* @param transform the ndarray to op
* @param dimension the dimension to iterate along
* @param numElements the desired number of elements in each fft
* @return the transformed array
*/
@Override
public IComplexNDArray ifftn(IComplexNDArray transform, int dimension, int numElements) {
if (numElements < 1)
throw new IllegalArgumentException("No elements specified");
int[] finalShape = ArrayUtil.replace(transform.shape(), dimension, numElements);
int[] axes = ArrayUtil.range(0, finalShape.length);
IComplexNDArray result = transform.dup();
int desiredElementsAlongDimension = result.size(dimension);
if (numElements > desiredElementsAlongDimension) {
result = ComplexNDArrayUtil.padWithZeros(result, finalShape);
} else if (numElements < desiredElementsAlongDimension)
result = ComplexNDArrayUtil.truncate(result, numElements, dimension);
return rawifftn(result, finalShape, axes);
}
/**
* Performs FFT along the first non singleton dimension of
* op. This means
*
* @param transform the ndarray to op
* @param dimension the dimension to iterate along
* @param numElements the desired number of elements in each fft
* along each dimension from each slice (note: each slice)
* @return the transformed array
*/
@Override
public IComplexNDArray fftn(IComplexNDArray transform, int dimension, int numElements) {
if (numElements < 1)
throw new IllegalArgumentException("No elements specified");
int[] finalShape = ArrayUtil.replace(transform.shape(), dimension, numElements);
int[] axes = ArrayUtil.range(0, finalShape.length);
IComplexNDArray result = transform.dup();
int desiredElementsAlongDimension = result.size(dimension);
if (numElements > desiredElementsAlongDimension)
result = ComplexNDArrayUtil.padWithZeros(result, finalShape);
else if (numElements < desiredElementsAlongDimension)
result = ComplexNDArrayUtil.truncate(result, numElements, dimension);
return rawfftn(result, finalShape, axes);
}
/**
* Computes the fft along the first non singleton dimension of op
* when it is a matrix
*
* @param transform the ndarray to op
* @param dimension the dimension to do fft along
* @param numElements the desired number of elements in each fft
* @return the fft of the specified ndarray
*/
@Override
public IComplexNDArray fftn(INDArray transform, int dimension, int numElements) {
return fftn(Nd4j.createComplex(transform), dimension, numElements);
}
/**
* FFT on the whole array (n is equal the first dimension shape)
*
* @param transform the matrix to op
* @return the ffted array
*/
@Override
public IComplexNDArray fftn(INDArray transform) {
return fftn(transform, transform.shape().length - 1, transform.shape()[transform.shape().length - 1]);
}
/**
* FFT on the whole array (n is equal the first dimension shape)
*
* @param transform the matrix to op
* @return the ffted array
*/
@Override
public IComplexNDArray fftn(IComplexNDArray transform) {
return rawfftn(transform, null, null);
}
@Override
public IComplexNDArray ifftn(IComplexNDArray transform, int dimension) {
return ifftn(transform, dimension, transform.shape()[dimension]);
}
@Override
public IComplexNDArray ifftn(IComplexNDArray transform) {
return rawifftn(transform, null, null);
}
@Override
public IComplexNDArray ifftn(INDArray transform) {
return ifftn(transform, transform.shape().length - 1, transform.size(transform.shape().length - 1));
}
//underlying ifftn
@Override
public IComplexNDArray rawifftn(IComplexNDArray transform, int[] shape, int[] axes) {
return doFFt(transform, shape, axes, true);
}
//underlying fftn
@Override
public IComplexNDArray rawfftn(IComplexNDArray transform, int[] shape, int[] axes) {
return doFFt(transform, shape, axes, false);
}
private IComplexNDArray fixShape(IComplexNDArray x, int[] shape, int axis, int n) {
if (shape[axis] > n) {
int[] newShape = ArrayUtil.copy(shape);
newShape[axis] = n;
x = ComplexNDArrayUtil.truncate(x, n, axis);
} else {
int[] newShape = ArrayUtil.copy(shape);
newShape[axis] = n;
x = ComplexNDArrayUtil.padWithZeros(x, newShape);
return x;
}
return x;
}
//underlying fftn
@Override
public IComplexNDArray rawifft(IComplexNDArray transform, int dimension) {
return rawifft(transform, transform.shape()[dimension], dimension);
}
protected IComplexNDArray doFFt(IComplexNDArray transform, int[] shape, int[] axes, boolean inverse) {
IComplexNDArray result = transform.dup();
if (shape == null)
shape = ArrayUtil.copy(result.shape());
boolean noAxes = false;
if (axes == null || axes.length < 1) {
noAxes = true;
axes = ArrayUtil.range(0, shape.length);
axes = ArrayUtil.reverseCopy(axes);
}
if (noAxes) {
for (int i : axes) {
if (i < 0)
i = shape.length + i;
transform = fixShape(transform, shape, i, shape[i]);
}
}
if (ArrayUtil.prod(shape) > ArrayUtil.prod(result.shape()))
result = ComplexNDArrayUtil.padWithZeros(result, shape);
return doInnerFft(result, shape, axes, inverse);
}
//the inner loop for an fft or ifft
protected IComplexNDArray doInnerFft(IComplexNDArray result, int[] shape, int[] axes, boolean inverse) {
for (int i = 0; i < axes.length; i++) {
result = inverse ? ifft(result, shape[axes[i]], axes[i]) : fft(result, shape[axes[i]], axes[i]);
}
return result;
}
}
