1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
|
/*=========================================================================
*
* Copyright NumFOCUS
*
* 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
*
* https://www.apache.org/licenses/LICENSE-2.0.txt
*
* 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.
*
*=========================================================================*/
// First include the header file to be tested:
#include "itkImageRandomConstIteratorWithIndex.h"
#include "itkImage.h"
#include "itkImageBufferRange.h"
#include "itkMersenneTwisterRandomVariateGenerator.h"
#include <gtest/gtest.h> // For iota.
#include <numeric>
// Tests that ImageRandomConstIteratorWithIndex is deterministic, when the initial seed and the next seed of the global
// MersenneTwisterRandomVariateGenerator are reset before creating the iterator.
TEST(ImageRandomConstIteratorWithIndex, IsDeterministicWhenGlobalRandomSeedsAreReset)
{
using PixelType = int;
const unsigned int Dimension{ 2 };
using ImageType = itk::Image<PixelType, Dimension>;
// Create just a small test image, but still having enough pixels for the iterator to pick different samples from.
const auto image = ImageType::New();
const itk::ImageRegion<Dimension> imageRegion(ImageType::SizeType::Filled(3));
image->SetRegions(imageRegion);
image->Allocate();
// Make sure that each pixel has a different value.
const itk::ImageBufferRange imageBufferRange(*image);
std::iota(imageBufferRange.begin(), imageBufferRange.end(), 0);
using itk::Statistics::MersenneTwisterRandomVariateGenerator;
for (const MersenneTwisterRandomVariateGenerator::IntegerType initialSeed : { 0, 1 })
{
const auto generateSamples = [initialSeed, image]() {
// Reset both the initial seed and the next seed of the global random variate generator.
MersenneTwisterRandomVariateGenerator::GetInstance()->SetSeed(initialSeed);
MersenneTwisterRandomVariateGenerator::ResetNextSeed();
itk::ImageRandomConstIteratorWithIndex<ImageType> iterator(image, image->GetRequestedRegion());
// Request just a small number of samples, for performance reasons. Note that even for this small number of
// samples, it is important to have the global seeds reset, in order to have a deterministic iteration.
iterator.SetNumberOfSamples(3);
std::vector<std::pair<PixelType, ImageType::IndexType>> samples{};
while (!iterator.IsAtEnd())
{
samples.push_back({ iterator.Get(), iterator.GetIndex() });
++iterator;
}
return samples;
};
// Expect the same samples when generating them twice with the same initial seed.
EXPECT_EQ(generateSamples(), generateSamples());
}
}
|
