types::ndarray<T, N> _transpose(types::ndarray<T, N> const &a,
long const l[N])
{
auto shape = a.shape();
types::array<long, N> shp;
for (unsigned long i = 0; i < N; ++i)
shp[i] = shape[l[i]];
types::ndarray<T, N> new_array(shp, __builtin__::None);
types::array<long, N> new_strides;
new_strides[N - 1] = 1;
std::transform(new_strides.rbegin(), new_strides.rend() - 1, shp.rbegin(),
new_strides.rbegin() + 1, std::multiplies<long>());
types::array<long, N> old_strides;
old_strides[N - 1] = 1;
std::transform(old_strides.rbegin(), old_strides.rend() - 1,
shape.rbegin(), old_strides.rbegin() + 1,
std::multiplies<long>());
auto iter = a.buffer, iter_end = a.buffer + a.flat_size();
for (long i = 0; iter != iter_end; ++iter, ++i) {
long offset = 0;
for (unsigned long s = 0; s < N; s++)
offset += ((i / old_strides[l[s]]) % shape[l[s]]) * new_strides[s];
new_array.buffer[offset] = *iter;
}
return new_array;
}
types::ndarray<T, types::array<long, std::tuple_size<pS>::value>>
rot90(types::ndarray<T, pS> const &expr, int k)
{
auto constexpr N = std::tuple_size<pS>::value;
if (k % 4 == 0)
return copy(expr);
types::array<long, N> shape = sutils::array(expr.shape());
if (k % 4 != 2)
std::swap(shape[0], shape[1]);
types::ndarray<T, types::array<long, N>> out(shape, __builtin__::None);
if (k % 4 == 1) {
for (int i = 0; i < shape[1]; ++i)
for (int j = 0; j < shape[0]; ++j)
out[shape[0] - 1 - j][i] = expr[i][j];
} else if (k % 4 == 2) {
for (int i = 0; i < shape[1]; ++i)
for (int j = 0; j < shape[0]; ++j)
out[shape[0] - 1 - j][shape[1] - 1 - i] = expr[j][i];
} else {
for (int i = 0; i < shape[1]; ++i)
for (int j = 0; j < shape[0]; ++j)
out[j][shape[1] - 1 - i] = expr[i][j];
}
return out;
}
types::ndarray<T,N> roll(types::ndarray<T,N> const& expr, long shift)
{
while(shift<0) shift+=expr.flat_size();
shift %=expr.flat_size();
types::ndarray<T,N> out(expr.shape(), __builtin__::None);
std::copy(expr.fbegin(), expr.fend() - shift, std::copy(expr.fend() - shift, expr.fend(), out.fbegin()));
return out;
}
types::ndarray<T,N> roll(types::ndarray<T,N> const& expr, long shift, long axis)
{
auto&& expr_shape = expr.shape();
while(shift<0) shift+=expr_shape[axis];
types::ndarray<T,N> out(expr_shape, __builtin__::None);
_roll(out.fbegin(), expr.fbegin(), shift, axis, expr_shape, utils::int_<N>());
return out;
}
types::ndarray<T,2> tril(types::ndarray<T,2> const& expr, int k = 0)
{
auto&& expr_shape = expr.shape();
types::ndarray<T,2> out(expr_shape, __builtin__::None);
for(int i=0; i<expr_shape[0]; ++i) {
auto out_i = out[i];
auto expr_i = expr[i];
for(long j=0 ; j<expr_shape[1]; ++j)
if( j - i <= k)
out_i[j] = expr_i[j];
else
out_i[j] = 0;
}
return out;
}