interp1

interp1#

Piecewise interpolation with various methods (linear, nearest, next, previous, spline).

template<typename OpX, typename OpV, typename OpXQ>
auto matx::interp1(const OpX &x, const OpV &v, const OpXQ &xq, InterpMethod method = InterpMethod::LINEAR)#

1D interpolation of samples at query points.

Interpolation is performed along the last dimension. All other dimensions must be of compatible size.

Template Parameters:

  • OpX – Type of sample points

  • OpV – Type of sample values

  • OpXQ – Type of query points

Parameters:

  • x – Sample points. Last dimension must be sorted in ascending order.

  • v – Sample values. Must have compatible dimensions with x.

  • xq – Query points where to interpolate. All dimensions except the last must be of compatible size with x and v (e.g. x and v can be vectors, and xq can be a matrix).

  • method – Interpolation method (LINEAR, NEAREST, NEXT, PREV, SPLINE)

Returns:

Operator that interpolates values at query points, with the same dimensions as xq.

template<typename OpX, typename OpV, typename OpXQ>
auto matx::interp1(const OpX &x, const OpV &v, const OpXQ &xq, const int (&axis)[1], InterpMethod method = InterpMethod::LINEAR)#

1D interpolation of samples at query points.

Interpolation is performed along the specified dimension. All other dimensions must be of compatible size.

Template Parameters:

  • OpX – Type of sample points

  • OpV – Type of sample values

  • OpXQ – Type of query points

Parameters:

  • x – Sample points. Last dimension must be sorted in ascending order.

  • v – Sample values. Must have compatible dimensions with x.

  • xq – Query points where to interpolate. All dimensions except the specified dimension must be of compatible size with x and v (e.g. x and v can be vectors, and xq can be a matrix).

  • axis – Dimension (of xq) along which to interpolate.

  • method – Interpolation method (LINEAR, NEAREST, NEXT, PREV, SPLINE)

Returns:

Operator that interpolates values at query points, with the same dimensions as xq.

Interpolation Methods#

enum class matx::InterpMethod#

Interpolation method enumeration.

Specifies the algorithm to use when performing interpolation between sample points.

Values:

enumerator LINEAR#

Linear interpolation between adjacent points.

enumerator NEAREST#

Uses the value at the nearest sample point.

enumerator NEXT#

Uses the value at the next sample point.

enumerator PREV#

Uses the value at the previous sample point.

enumerator SPLINE#

Cubic spline interpolation, using not-a-knot boundary conditions.

Examples#

Linear Interpolation (default):

auto x = make_tensor<TestType>({5});
x.SetVals({0.0, 1.0, 3.0, 3.5, 4.0});

auto v = make_tensor<TestType>(x.Shape());
v.SetVals({0.0, 2.0, 1.0, 3.0, 4.0});

auto xq = make_tensor<TestType>({6});
xq.SetVals({-1.0, 0.0, 0.25, 1.0, 1.5, 5.0});

auto vq_linear = make_tensor<TestType>({xq.Size(0)});
vq_linear.SetVals({0.0, 0.0, 0.5, 2.0, 1.75, 4.0});

auto vq_nearest = make_tensor<TestType>({xq.Size(0)});
vq_nearest.SetVals({0.0, 0.0, 0.0, 2.0, 2.0, 4.0});

auto vq_next = make_tensor<TestType>({xq.Size(0)});
vq_next.SetVals({0.0, 0.0, 2.0, 2.0, 1.0, 4.0});

auto vq_prev = make_tensor<TestType>({xq.Size(0)});
vq_prev.SetVals({0.0, 0.0, 0.0, 2.0, 2.0, 4.0});

auto vq_spline = make_tensor<TestType>({xq.Size(0)});
vq_spline.SetVals({-10.7391, 0.0, 1.1121, 2.0, 1.3804, -8.1739});



auto out_linear = make_tensor<TestType>({xq.Size(0)});
(out_linear = interp1(x, v, xq, InterpMethod::LINEAR)).run(exec);

Nearest Neighbor Interpolation:

auto out_nearest = make_tensor<TestType>({xq.Size(0)});
(out_nearest = interp1(x, v, xq, InterpMethod::NEAREST)).run(exec);