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Upgrade arange #83

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ff1c850
CountingExpression: use std::size_t instead of int
PaulPrice Jun 8, 2020
f56bc38
arange: support floating-point
PaulPrice Jun 8, 2020
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38 changes: 19 additions & 19 deletions include/ndarray/arange.h
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Original file line number Diff line number Diff line change
Expand Up @@ -30,11 +30,11 @@ namespace ndarray {
*/
template <>
struct ExpressionTraits<detail::CountingExpression> {
typedef int Element;
typedef std::size_t Element;
typedef boost::mpl::int_<1> ND;
typedef boost::counting_iterator<int> Iterator;
typedef int Value;
typedef int Reference;
typedef boost::counting_iterator<std::size_t> Iterator;
typedef std::size_t Value;
typedef std::size_t Reference;
};

namespace detail {
Expand All @@ -52,11 +52,11 @@ class CountingExpression : public ExpressionBase<CountingExpression> {
typedef ExpressionTraits<CountingExpression>::Iterator Iterator;
typedef ExpressionTraits<CountingExpression>::Value Value;
typedef ExpressionTraits<CountingExpression>::Reference Reference;
typedef Vector<int,1> Index;
typedef Vector<std::size_t,1> Index;

CountingExpression(int stop=0) : _stop(stop) { NDARRAY_ASSERT(stop >= 0); }
CountingExpression(std::size_t stop=0) : _stop(stop) { NDARRAY_ASSERT(stop >= 0); }

Reference operator[](int n) const {
Reference operator[](std::size_t n) const {
return n;
}

Expand All @@ -68,7 +68,7 @@ class CountingExpression : public ExpressionBase<CountingExpression> {
return Iterator(_stop);
}

template <int P> int getSize() const {
template <std::size_t P> std::size_t getSize() const {
BOOST_STATIC_ASSERT(P==0);
return _stop;
}
Expand All @@ -78,39 +78,39 @@ class CountingExpression : public ExpressionBase<CountingExpression> {
}

private:
int _stop;
std::size_t _stop;
};

template <typename T>
class RangeTransformer {
T _offset;
T _scale;
public:
typedef int argument_type;
typedef std::size_t argument_type;
typedef T result_type;

explicit RangeTransformer(T const & offset, T const & scale) : _offset(offset), _scale(scale) {}

T operator()(int n) const { return static_cast<T>(n) * _scale + _offset; }
T operator()(std::size_t n) const { return static_cast<T>(n) * _scale + _offset; }
};

} // namespace detail

/// @brief Create 1D Expression that contains integer values in the range [0,stop).
inline detail::CountingExpression arange(int stop) {
inline detail::CountingExpression arange(std::size_t stop) {
return detail::CountingExpression(stop);
}

/// @brief Create 1D Expression that contains integer values in the range [start,stop) with increment step.
inline detail::UnaryOpExpression< detail::CountingExpression, detail::RangeTransformer<int> >
arange(int start, int stop, int step = 1) {
template <typename T>
detail::UnaryOpExpression< detail::CountingExpression, detail::RangeTransformer<T> >
arange(T start, T stop, T step = 1) {
NDARRAY_ASSERT(step != 0);
int size = stop - start;
if (step < -1) ++size;
if (step > 1) --size;
size /= step;
T const diff = stop - start;
NDARRAY_ASSERT((diff > 0 && step > 0) || (diff < 0 && step < 0));
std::size_t const size = diff/step;
return vectorize(
detail::RangeTransformer<int>(start,step),
detail::RangeTransformer<T>(start,step),
detail::CountingExpression(size)
);
}
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54 changes: 54 additions & 0 deletions tests/ndarray.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -628,3 +628,57 @@ BOOST_AUTO_TEST_CASE(issue3) {
BOOST_CHECK_EQUAL(s5.getSize<3>(), 2);
BOOST_CHECK_EQUAL(s5.getSize<4>(), 1);
}

BOOST_AUTO_TEST_CASE(arangeInt) {
std::size_t const size = 10;
// Basic use
{
ndarray::Array<std::size_t, 1, 1> values = ndarray::copy(ndarray::arange(size));
BOOST_CHECK_EQUAL(values.getNumElements(), size);
for (std::size_t ii = 0; ii < size; ++ii) {
BOOST_CHECK_EQUAL(values[ii], ii);
}
}
{
ndarray::Array<std::size_t, 1, 1> values = ndarray::copy(ndarray::arange(0UL, size));
BOOST_CHECK_EQUAL(values.getNumElements(), size);
for (std::size_t ii = 0; ii < size; ++ii) {
BOOST_CHECK_EQUAL(values[ii], ii);
}

}

// Expanded use
std::vector<int> startList = {0, 3, 7, 123};
std::vector<int> stepList = {1, 2, 3, 10, -1, -2, -3, -10};
{
for (int step : stepList) {
for (int start : startList) {
int stop = start + size*step;
ndarray::Array<int, 1, 1> values = ndarray::copy(ndarray::arange(start, stop, step));
BOOST_CHECK_EQUAL(values.getNumElements(), size);
for (std::size_t ii = 0; ii < size; ++ii) {
int expect = start + ii*step;
BOOST_CHECK_EQUAL(values[ii], expect);
}
}
}
}
}

BOOST_AUTO_TEST_CASE(arangeFloat) {
std::size_t const size = 10;
std::vector<float> startList = {0.0, 123.45};
std::vector<float> stepList = {1.0, 0.1, 1.23};
for (float step : stepList) {
for (float start : startList) {
float stop = start + size*step;
ndarray::Array<float, 1, 1> values = ndarray::copy(ndarray::arange(start, stop, step));
BOOST_CHECK_EQUAL(values.getNumElements(), size);
for (std::size_t ii = 0; ii < size; ++ii) {
float expect = start + ii*step;
BOOST_CHECK_EQUAL(values[ii], expect);
}
}
}
}