From 200f2f9a5fe3245d5c78d178d942a942713e1923 Mon Sep 17 00:00:00 2001
From: Wissam Boussella <wissam.boussella@cea.fr>
Date: Thu, 20 Mar 2025 15:57:51 +0000
Subject: [PATCH] [Transpose] update output DataFormat based on input
 DataFormat and ouputDimsOrder

---
 include/aidge/data/DataFormat.hpp          |  18 ++++
 python_binding/data/pybind_DataFormat.cpp  |   1 +
 src/data/DataFormat.cpp                    |  46 +++++++++
 src/operator/Transpose.cpp                 |   7 ++
 unit_tests/operator/Test_TransposeImpl.cpp | 110 +++++++++++++++++++++
 5 files changed, 182 insertions(+)

diff --git a/include/aidge/data/DataFormat.hpp b/include/aidge/data/DataFormat.hpp
index 4df854a1e..d89eb24cd 100644
--- a/include/aidge/data/DataFormat.hpp
+++ b/include/aidge/data/DataFormat.hpp
@@ -83,6 +83,24 @@ using DataFormatTranspose = std::array<std::size_t, 5>;
  */
 DataFormatTranspose getPermutationMapping(const DataFormat& src, const DataFormat& dst);
 
+/**
+ * @brief Determine the output data format after applying a transpose operation.
+ *
+ * This function computes the new data format after transposing a tensor.
+ *
+ * It follows these steps:
+ *   1. Retrieves the permutation mapping from the input format.
+ *   2. Applies the given output dimensions order to compute the new permutation.
+ *   3. Identifies the corresponding data format after applying the new permutation.
+ * 
+ * @param inputDataFormat The data format of the input tensor.
+ * @param outputDimsOrder The permutation applied to the input tensor's dimensions.
+ * @return DataFormat The computed output data format after applying the permutation.
+ *
+ * @pre `outputDimsOrder` must be a valid permutation of the format's dimensions.
+ */
+DataFormat getTransposedDataFormat(const DataFormat inputDataFormat, const std::array<std::size_t, 5> outputDimsOrder);
+
 } // namespace Aidge
 
 namespace {
diff --git a/python_binding/data/pybind_DataFormat.cpp b/python_binding/data/pybind_DataFormat.cpp
index 5308fb302..354911c33 100644
--- a/python_binding/data/pybind_DataFormat.cpp
+++ b/python_binding/data/pybind_DataFormat.cpp
@@ -67,6 +67,7 @@ void init_DataFormat(py::module& m) {
     bindEnum<DataFormat>(m, "dformat");
     m.def("format_as", (const char* (*)(DataFormat)) &format_as, py::arg("df"));
     m.def("get_permutation_mapping", &getPermutationMapping, py::arg("src"), py::arg("dst"));
+    m.def("get_transposed_data_format", &getTransposedDataFormat, py::arg("input_data_format"), py::arg("output_dims_order"));
 }
 
 } // namespace Aidge
diff --git a/src/data/DataFormat.cpp b/src/data/DataFormat.cpp
index 8b7460b3d..095ef9368 100644
--- a/src/data/DataFormat.cpp
+++ b/src/data/DataFormat.cpp
@@ -51,6 +51,25 @@ static std::size_t getNbDimensions(DataFormat dformat) {
     return nbDimensions[static_cast<std::size_t>(dformat)];
 }
 
+/**
+ * @brief Get the DataFormat corresponding to a given ``DataFormatTranspose``.
+ *
+ * @param perm The permutation vector.
+ * @return DataFormat The matching DataFormat, or DataFormat::Default if not found.
+ */
+static DataFormat getDataFormatFromPermutation(const DataFormatTranspose& perm, const unsigned int nbDims) { 
+    for (size_t i = 0; i < NB_DFORMAT; ++i) {
+        DataFormat candidateFormat = static_cast<DataFormat>(i);
+        const DataFormatTranspose& candidatePerm = getPermutationFromNCHW(candidateFormat);
+
+        if (std::equal(candidatePerm.begin(), candidatePerm.begin() + nbDims, perm.begin())) {
+            return candidateFormat;
+        }
+    }
+    Log::warn("No matching DataFormat found for the given permutation : {}", perm);
+    return DataFormat::Default;  
+}
+
 DataFormatTranspose getPermutationMapping(const DataFormat& src, const DataFormat& dst) {
     AIDGE_ASSERT((src != DataFormat::Any && dst != DataFormat::Any), "Permutation is not defined for DataFormat::Any");
     if (src == DataFormat::Default || dst == DataFormat::Default || src == dst) {
@@ -78,4 +97,31 @@ DataFormatTranspose getPermutationMapping(const DataFormat& src, const DataForma
 
     return src_to_dst;
 }
+
+/**
+ * @brief Applies one permutation to another.
+ *
+ * Given an initial permutation `perm1` and another permutation `perm2`,
+ * this function returns a new permutation that results from applying `perm2` to `perm1`.
+ *
+ * @param perm1 The base permutation (original ordering → intermediate ordering).
+ * @param perm2 The permutation to apply (intermediate ordering → final ordering).
+    * @return DataFormatTranspose The resultng permutation (original ordering → final ordering).
+ */
+static DataFormatTranspose applyPermutation(const DataFormatTranspose& perm1, const DataFormatTranspose& perm2) {
+    DataFormatTranspose permuted{};
+    for (std::size_t i = 0; i < perm1.size(); ++i) {
+        permuted[i] = perm2[perm1[i]];
+    }
+    return permuted;
+}
+
+DataFormat getTransposedDataFormat(const DataFormat inputDataFormat, const std::array<std::size_t, 5> outputDimsOrder){
+    const DataFormatTranspose permFromInput = getPermutationFromNCHW(inputDataFormat);
+    const DataFormatTranspose newPerm = applyPermutation(permFromInput, outputDimsOrder);
+    
+    const unsigned int nbDims = getNbDimensions(inputDataFormat);
+
+    return getDataFormatFromPermutation(newPerm, nbDims);
+}
 } // namespace Aidge
\ No newline at end of file
diff --git a/src/operator/Transpose.cpp b/src/operator/Transpose.cpp
index f9d612353..f9e469476 100644
--- a/src/operator/Transpose.cpp
+++ b/src/operator/Transpose.cpp
@@ -77,7 +77,14 @@ bool Aidge::Transpose_Op::forwardDims(bool /*allowDataDependency*/) {
             AIDGE_ASSERT(i == outputDimsOrder()[i],
                 "Permutation vector ({}) must be the identity above the input tensor rank ({}).", outputDimsOrder(), getInput(0)->dims());
         }
+        
         mOutputs[0]->resize(outputDims);
+
+        // Set the data format of the output tensor
+        DataFormatTranspose outputDimsArray;
+        std::copy_n(outputDimsOrder().begin(), outputDimsOrder().size(), outputDimsArray.begin());
+
+        mOutputs[0]->setDataFormat(getTransposedDataFormat(getInput(0)->dataFormat(), outputDimsArray));
         return true;
     }
     return false;
diff --git a/unit_tests/operator/Test_TransposeImpl.cpp b/unit_tests/operator/Test_TransposeImpl.cpp
index 02b338dd2..f852c3fe0 100644
--- a/unit_tests/operator/Test_TransposeImpl.cpp
+++ b/unit_tests/operator/Test_TransposeImpl.cpp
@@ -200,3 +200,113 @@ TEST_CASE("[cpu/operator] Transpose(forward)") {
         REQUIRE(*(op->getOutput(0)) == *output);
     }
 }
+
+TEST_CASE("[cpu/operator] Transpose DataFormat") {
+    SECTION("NCHW to NHWC"){
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,3,224,450}));
+        input->setDataFormat(Aidge::DataFormat::NCHW);
+        auto transposeNode = Transpose({0,2,3,1});
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode -> getOperator());
+        op->associateInput(0,input);
+        op->forwardDims();
+
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NHWC);
+    }
+    SECTION("NHWC to NCHW"){
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,3,224,450}));
+        input->setDataFormat(Aidge::DataFormat::NHWC);
+        auto transposeNode = Transpose({0,3,1,2});
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode -> getOperator());
+        op->associateInput(0,input);
+        op->forwardDims();
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NCHW);
+    }
+    SECTION("CHWN to NCHW") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({3,224,450,16}));
+        input->setDataFormat(Aidge::DataFormat::CHWN);
+        auto transposeNode = Transpose({3,0,1,2});
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+        op->forwardDims();
+
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NCHW);
+    }
+
+    SECTION("NCDHW to NDHWC") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,3,8,224,450}));
+        input->setDataFormat(Aidge::DataFormat::NCDHW);
+        auto transposeNode = Transpose({0,2,3,4,1});
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+        op->forwardDims();
+
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NDHWC);
+    }
+
+    SECTION("NDHWC to NCDHW") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,8,224,450,3}));
+        input->setDataFormat(Aidge::DataFormat::NDHWC);
+        auto transposeNode = Transpose({0,4,1,2,3});
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+        op->forwardDims();
+
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NCDHW);
+    }
+
+    SECTION("CDHWN to NCDHW") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({3,8,224,450,16}));
+        input->setDataFormat(Aidge::DataFormat::CDHWN);
+        auto transposeNode = Transpose({4,0,1,2,3});
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+        op->forwardDims();
+
+
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NCDHW);
+    }
+
+    SECTION("(Identity) NCHW to NCHW)") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,3,224,450}));
+        input->setDataFormat(Aidge::DataFormat::NCHW);
+        auto transposeNode = Transpose({0,1,2,3}); // Identity permutation
+
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+        op->forwardDims();
+
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::NCHW);
+    }
+
+    SECTION("Default to Default") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,3,224,450}));
+        input->setDataFormat(Aidge::DataFormat::Default);
+        auto transposeNode = Transpose({0,2,3,1});
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+
+        op->forwardDims();
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::Default);
+        //Should print a Log::Warning
+    }
+
+    SECTION("Invalid Format Handling") {
+        std::shared_ptr<Tensor> input = std::make_shared<Tensor>(std::vector<std::size_t>({16,3,224,450}));
+        input->setDataFormat(Aidge::DataFormat::NCHW);
+        auto transposeNode = Transpose({0,2,1,3});
+        auto op = std::static_pointer_cast<OperatorTensor>(transposeNode->getOperator());
+        op->associateInput(0, input);
+
+        op->forwardDims();
+        REQUIRE(op->getOutput(0)->dataFormat() == DataFormat::Default);
+        //Should print a Log::Warning
+    }
+
+}
+
-- 
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