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median.cpp
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median.cpp
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/*******************************************************
* Copyright (c) 2014, ArrayFire
* All rights reserved.
*
* This file is distributed under 3-clause BSD license.
* The complete license agreement can be obtained at:
* http://arrayfire.com/licenses/BSD-3-Clause
********************************************************/
#include <af/dim4.hpp>
#include <af/defines.h>
#include <af/statistics.h>
#include <af/index.h>
#include <af/arith.h>
#include <af/data.h>
#include <handle.hpp>
#include <err_common.hpp>
#include <backend.hpp>
#include <sort.hpp>
#include <math.hpp>
#include <cast.hpp>
using namespace detail;
using af::dim4;
template<typename T>
static double median(const af_array& in)
{
dim_t nElems = getInfo(in).elements();
dim4 dims(nElems, 1, 1, 1);
af_array temp = 0;
AF_CHECK(af_moddims(&temp, in, 1, dims.get()));
const Array<T> input = getArray<T>(temp);
// Shortcut cases for 1 or 2 elements
if(nElems == 1) {
T result;
AF_CHECK(af_get_data_ptr((void*)&result, in));
return result;
} else if(nElems == 2) {
T result[2];
AF_CHECK(af_get_data_ptr((void*)&result, in));
if (input.isFloating()) {
return division(result[0] + result[1], 2.0);
} else {
return division(result[0] + result[1], 2.0);
}
}
double mid = (nElems + 1) / 2;
af_seq mdSpan[1]= {af_make_seq(mid-1, mid, 1)};
Array<T> sortedArr = sort<T, true>(input, 0);
af_array sarrHandle = getHandle<T>(sortedArr);
double result;
T resPtr[2];
af_array res = 0;
AF_CHECK(af_index(&res, sarrHandle, 1, mdSpan));
AF_CHECK(af_get_data_ptr((void*)&resPtr, res));
AF_CHECK(af_release_array(res));
AF_CHECK(af_release_array(sarrHandle));
AF_CHECK(af_release_array(temp));
if (nElems % 2 == 1) {
result = resPtr[0];
} else {
if (input.isFloating()) {
result = division(resPtr[0] + resPtr[1], 2);
} else {
result = division((float)resPtr[0] + (float)resPtr[1], 2);
}
}
return result;
}
template<typename T>
static af_array median(const af_array& in, const dim_t dim)
{
const Array<T> input = getArray<T>(in);
// Shortcut cases for 1 element along selected dimension
if(input.dims()[dim] == 1) {
Array<T> result = copyArray<T>(input);
return getHandle<T>(result);
}
Array<T> sortedIn = sort<T, true>(input, dim);
int dimLength = input.dims()[dim];
double mid = (dimLength + 1) / 2;
af_array left = 0;
af_seq slices[4] = {af_span, af_span, af_span, af_span};
slices[dim] = af_make_seq(mid-1.0, mid-1.0, 1.0);
af_array sortedIn_handle = getHandle<T>(sortedIn);
AF_CHECK(af_index(&left, sortedIn_handle, input.ndims(), slices));
if (dimLength % 2 == 1) {
// mid-1 is our guy
if (input.isFloating()) return left;
// Return as floats for consistency
af_array out;
AF_CHECK(af_cast(&out, left, f32));
AF_CHECK(af_release_array(left));
AF_CHECK(af_release_array(sortedIn_handle));
return out;
} else {
// ((mid-1)+mid)/2 is our guy
dim4 dims = input.dims();
af_array right = 0;
slices[dim] = af_make_seq(mid, mid, 1.0);
AF_CHECK(af_index(&right, sortedIn_handle, dims.ndims(), slices));
af_array sumarr = 0;
af_array carr = 0;
af_array result = 0;
dim4 cdims = dims;
cdims[dim] = 1;
AF_CHECK(af_constant(&carr, 0.5, cdims.ndims(), cdims.get(), input.isDouble() ? f64 : f32));
if (!input.isFloating()) {
af_array lleft, rright;
AF_CHECK(af_cast(&lleft, left, f32));
AF_CHECK(af_cast(&rright, right, f32));
AF_CHECK(af_release_array(left));
AF_CHECK(af_release_array(right));
left = lleft;
right = rright;
}
AF_CHECK(af_add(&sumarr, left, right, false));
AF_CHECK(af_mul(&result, sumarr, carr, false));
AF_CHECK(af_release_array(left));
AF_CHECK(af_release_array(right));
AF_CHECK(af_release_array(sumarr));
AF_CHECK(af_release_array(carr));
AF_CHECK(af_release_array(sortedIn_handle));
return result;
}
}
af_err af_median_all(double *realVal, double *imagVal, const af_array in)
{
try {
ArrayInfo info = getInfo(in);
af_dtype type = info.getType();
switch(type) {
case f64: *realVal = median<double>(in); break;
case f32: *realVal = median<float >(in); break;
case s32: *realVal = median<int >(in); break;
case u32: *realVal = median<uint >(in); break;
case s16: *realVal = median<short >(in); break;
case u16: *realVal = median<ushort>(in); break;
case u8: *realVal = median<uchar >(in); break;
default : TYPE_ERROR(1, type);
}
}
CATCHALL;
return AF_SUCCESS;
}
af_err af_median(af_array* out, const af_array in, const dim_t dim)
{
try {
ARG_ASSERT(2, (dim >= 0 && dim <= 4));
af_array output = 0;
ArrayInfo info = getInfo(in);
af_dtype type = info.getType();
switch(type) {
case f64: output = median<double>(in, dim); break;
case f32: output = median<float >(in, dim); break;
case s32: output = median<int >(in, dim); break;
case u32: output = median<uint >(in, dim); break;
case s16: output = median<short >(in, dim); break;
case u16: output = median<ushort>(in, dim); break;
case u8: output = median<uchar >(in, dim); break;
default : TYPE_ERROR(1, type);
}
std::swap(*out, output);
}
CATCHALL;
return AF_SUCCESS;
}