update Resize operator

Context

issue : aidge#181 (closed)

Modified files

Detailed major modifications

TODO

• kernel works but should be reworked

include/aidge/backend/cpu/data/Interpolation.hpp

+/********************************************************************************
+ * Copyright (c) 2024 CEA-List
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License 2.0 which is available at
+ * http://www.eclipse.org/legal/epl-2.0.
+ *
+ * SPDX-License-Identifier: EPL-2.0
+ *
+ ********************************************************************************/
+
+#ifndef AIDGE_CPU_DATA_INTERPOLATION_H_
+#define AIDGE_CPU_DATA_INTERPOLATION_H_
+
+#include <vector>
+
+#include <aidge/data/Interpolation.hpp>
+#include <aidge/utils/Types.h>
+
+namespace Aidge {
+class InterpolationCPU : public Interpolation {
+  public:
+    /*
+     * @brief Interpolates values given via input in given mode.
+     *
+     * Values are contiguously arranged in a "square" shape around the point to
+     * interpolate. Depending on interpolation mode.
+     * The point that will be interpolated is located right in the
+     * middle of all points.
+     * Immediate neighbours :
+     * 1D interp :     2D interp :
+     *                 . . . . . .
+     * . . 1 2 . .     . . . . . .
+     *                 . . 1 2 . .
+     *                 . . 3 4 . .
+     *                 . . . . . .
+     *                 . . . . . .
+     *
+     * 2 neighbours :
+     * 1D interp :         2D interp :
+     *                   .  .  .  .  .  .  . .
+     *                   .  .  .  .  .  .  . .
+     * . . 1 2 3 4 . .   .  .  1  2  3  4  . .
+     *                   .  .  5  6  7  8  . .
+     *                   .  .  9 10 11 12  . .
+     *                   .  . 13 14 15 16  . .
+     *                   .  .  .  .  .  .  . .
+     *                   .  .  .  .  .  .  . .
+     *
+     * @param[in] originalCoords: coord of the point to interpolate in the
+     * original picture. These coords are generated with
+     * Interpolation::untransformCoords(coordsInInterpolatedTensor)
+     * @param[in] points : points to interpolate, arranged in a vector of a
+     * pairs ((point_coord), value) :
+     * [[[X1, X2, ..., XN], Xval], ...., [[A1, A2, ..., AN],Aval]].
+     * With :
+     * - N: the number of dimensions.
+     * - A: the number of points of the grid to interpolate.
+     * - All coordinates expressed in originalTensor frame.
+     * @param[in] interpMode: interpolation mode
+     * @return interpolated value
+     */
+    template <typename T>
+    static T interpolate(const std::vector<float> &coordsToInterpolate,
+                         const std::set<Point<T>> &points,
+                         const Mode interpMode = Interpolation::Mode::Linear);
+
+    /**
+     * @brief performs linear interpolation on given points.
+     * @param[in] values: values to interpolate, since we only do an average of
+     * all values, their indexes isn't useful.
+     * @return interpolated value
+     */
+    template <typename T>
+    static T linear(const std::vector<float> &originalCoords,
+                    const std::set<Point<T>> &points);
+
+    /**
+     * @brief performs nearest interpolation on given points.
+     * @note it is a wrapper for linearRecurse() private method
+     * @param[in] coordsToInterpolate: coordinates to interpolate
+     * @param[in] points: points to interpolate
+     * @param[in] interpMode: interpolation method, must be a Nearest...
+     * otherwise function will throw an error.
+     * @return interpolated value
+     */
+    template <typename T>
+    static T nearest(const std::vector<float> &coordsToInterpolate,
+                     const std::set<Point<T>> &points,
+                     const Interpolation::Mode nearestMode);
+
+  private:
+    /**
+     * @brief actual linear interpolation function.
+     * will :
+     * - Split all points along each dimension depending of if their coords at
+     * idx alongDim are above or under coordsToInterpolate until they are
+     * 1-to-1.
+     * - Perform interpolation in 2 leftover points and return interpolated 
+     * point to parent call with a set of size 1.
+     * - repeat until all dimensions have been interpolated.
+     * @param[in] coordsToInterpolate: coordinates to interpolate
+     * @param[in] points: points to interpolate
+     * @param[in] alongDim: discriminant on along which dimension are being
+     * segregated.
+     * @return
+     */
+    template <typename T>
+    static std::set<Interpolation::Point<T>>
+    linearRecurse(const std::vector<float> &coordsToInterpolate,
+                  const std::set<Point<T>> &points,
+                  const DimIdx_t alongDim = 0);
+};
+
+} // namespace Aidge
+
+#endif // AIDGE_CPU_DATA_INTERPOLATION_H_