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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.Op;
import org.nd4j.linalg.api.ops.impl.transforms.VectorFFT;
import org.nd4j.linalg.api.ops.impl.transforms.VectorIFFT;
import org.nd4j.linalg.factory.Nd4j;
import org.nd4j.linalg.util.ArrayUtil;
import org.nd4j.linalg.util.ComplexNDArrayUtil;
/**
* Default FFT instance
* that will work that is backend agnostic.
*
* @author Adam Gibson
*/
public class DefaultFFTInstance extends BaseFFTInstance {
/**
* 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, int dimension) {
IComplexNDArray inputC = Nd4j.createComplex(transform);
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(getFftOp(inputC, numElements));
else {
int[] finalShape = ArrayUtil.replace(transform.shape(), dimension, numElements);
IComplexNDArray transform2 = Nd4j.createComplex(transform);
IComplexNDArray result = transform2.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 rawfft(result, numElements, dimension);
}
}
/**
* 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, int dimension) {
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(getFftOp(inputC, numElements));
else
return rawfft(inputC, numElements, dimension);
}
/**
* IFFT along a particular dimension
*
* @param transform the ndarray to op
* @param numElements the desired number of elements in each fft
* @param dimension the dimension to do fft along
* @return the iffted output
*/
@Override
public IComplexNDArray ifft(INDArray transform, int numElements, int dimension) {
IComplexNDArray inputC = Nd4j.createComplex(transform);
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(getIfftOp(inputC, numElements));
else
return rawifft(inputC, numElements, dimension);
}
/**
* 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 ifft(IComplexNDArray inputC, int numElements, int dimension) {
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(getIfftOp(inputC, numElements));
else {
return rawifft(inputC, numElements, dimension);
}
}
/**
* 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 ifft(INDArray transform, int numElements) {
IComplexNDArray inputC = Nd4j.createComplex(transform);
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(getIfftOp(inputC, numElements));
else {
return rawifft(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 ifft(IComplexNDArray inputC) {
if (inputC.isVector())
return (IComplexNDArray) Nd4j.getExecutioner().execAndReturn(getIfftOp(inputC, inputC.length()));
else
return rawifft(inputC, inputC.size(inputC.shape().length - 1), inputC.shape().length - 1);
}
/**
* Underlying fft algorithm
*
* @param transform the ndarray to op
* @param n the desired number of elements
* @param dimension the dimension to do fft along
* @return the transformed ndarray
*/
@Override
public IComplexNDArray rawfft(IComplexNDArray transform, int n, int dimension) {
IComplexNDArray result = transform.dup();
result = preProcess(result, transform, n, dimension);
Nd4j.getExecutioner().iterateOverAllRows(getFftOp(result, n));
result = postProcess(result, dimension);
return result;
}
@Override
public IComplexNDArray rawifft(IComplexNDArray transform, int n, int dimension) {
IComplexNDArray result = transform.dup();
result = preProcess(result, transform, n, dimension);
Nd4j.getExecutioner().iterateOverAllRows(getIfftOp(result, n));
result = postProcess(result, dimension);
return result;
}
protected IComplexNDArray postProcess(IComplexNDArray result, int dimension) {
if (dimension != result.shape().length - 1)
result = result.swapAxes(result.shape().length - 1, dimension);
return result;
}
protected IComplexNDArray preProcess(IComplexNDArray result, IComplexNDArray transform, int n, int dimension) {
if (dimension < 0)
dimension = transform.shape().length - 1 - dimension;
if (transform.size(dimension) != n) {
int[] shape = ArrayUtil.copy(result.shape());
shape[dimension] = n;
if (transform.size(dimension) > n) {
result = ComplexNDArrayUtil.truncate(result, n, dimension);
} else
result = ComplexNDArrayUtil.padWithZeros(result, shape);
}
if (dimension != result.shape().length - 1)
result = result.swapAxes(result.shape().length - 1, dimension);
return result;
}
protected Op getIfftOp(INDArray arr, int n) {
return new VectorIFFT(arr, n);
}
protected Op getFftOp(INDArray arr, int n) {
return new VectorFFT(arr, n);
}
}
