Slice
=====

.. cpp:class:: numpy::Slice

   Core array class in the numpy namespace.

Example
-------

.. code-block:: cpp

   #include <numpy/np_ndarray.h>
   using namespace numpy;

   // Use Slice
   Slice obj;
   // ... operations ...

Constructors
------------

.. list-table::
   :widths: 55 25 20
   :header-rows: 1

   * - Signature
     - Location
     - Example
   * - ``Slice(std::optional<ssize_t>stop\_)``
     - NP_INDEX_TYPES.H:30
     - 
   * - ``Slice(std::optional<ssize_t>start\_, std::optional<ssize_t>stop\_)``
     - NP_INDEX_TYPES.H:31
     - 
   * - ``Slice(std::optional<ssize_t>start\_, std::optional<ssize_t>stop\_, std::optional<ssize_t>step\_)``
     - NP_INDEX_TYPES.H:33
     - 

Logical
-------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``Slice all()``
     - Slice
     - NP_INDEX_TYPES.H:37
     - :ref:`View <example-slice-all-0>`

Other Methods
-------------

.. list-table::
   :widths: 40 20 15 25
   :header-rows: 1

   * - Signature
     - Return Type
     - Location
     - Example
   * - ``Slice from(ssize_tstart\_)``
     - Slice
     - NP_INDEX_TYPES.H:38
     - :ref:`View <example-slice-from-1>`
   * - ``size_t length(size_tdim_size)``
     - size_t
     - NP_INDEX_TYPES.H:81
     - :ref:`View <example-slice-length-2>`
   * - ``Slice range(ssize_tstart\_, ssize_tstop\_)``
     - Slice
     - NP_INDEX_TYPES.H:40
     - :ref:`View <example-slice-range-3>`
   * - ``Slice stepped(ssize_tstart\_, ssize_tstop\_, ssize_tstep\_)``
     - Slice
     - NP_INDEX_TYPES.H:41
     - 
   * - ``Slice to(ssize_tstop\_)``
     - Slice
     - NP_INDEX_TYPES.H:39
     - :ref:`View <example-slice-to-4>`


Code Examples
-------------

The following examples are extracted from the test suite.

.. _example-slice-all-0:

.. dropdown:: all (np_test_4_all.cpp:23928)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 23918
      :emphasize-lines: 11

                              }
                          }
                      }
      
                      auto result = numpy::einsum<numpy::float64>("ijk->ik", {A});
      
                      if (result.getShape()[0] != 2 || result.getShape()[1] != 2) {
                          throw std::runtime_error("einsum partial sum shape wrong");
                      }
      
                      // Sum over j: 1+2+3 = 6 for all (i,k) positions
                      if (std::abs(result.getElementAt({0, 0}) - 6.0) > 1e-10 ||
                          std::abs(result.getElementAt({1, 1}) - 6.0) > 1e-10) {
                          throw std::runtime_error("einsum partial sum values wrong");
                      }
      
                      // std::cout << "  OK: Partial sum: 'ijk->ik'\n";
                  }
      
                  // Test 5: Size-1 dimension handling
                  {

.. _example-slice-from-1:

.. dropdown:: from (np_test_2_all.cpp:3651)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 3641
      :emphasize-lines: 11

                arr.setElementAt({ i, j }, static_cast<double>(i * 4 + j));
              }
            }
      
            auto rotated = rot90(arr, 1);
            if (!(rotated.getShape() == std::vector<size_t>({ 4, 3 }))) {
                std::string description = std::string("testRotationFlipOperations():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(rotated.getShape() == std::vector<size_t>({ 4, 3 }))";
                std::cout << std::string("[FAIL] ") + description << std::endl;
                throw std::runtime_error(description);
            }
            // For 90-degree counter-clockwise rotation: (i,j) -> (m-1-j, i), so (0,0) gets value from (0,3)
            if (!(isApproxEqualMCO(rotated.getElementAt({ 0, 0 }), arr.getElementAt({ 0, 3 })))) {
                std::string description = std::string("testRotationFlipOperations():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(isApproxEqualMCO(rotated.getElementAt({ 0, 0 }), arr.getElementAt({ 0, 3 })))";
                std::cout << std::string("[FAIL] ") + description << std::endl;
                throw std::runtime_error(description);
            }
      
            // Test rot90 with k=0 (no rotation)
            auto no_rot = rot90(arr, 0);
            if (!(no_rot.getShape() == arr.getShape())) {
                std::string description = std::string("testRotationFlipOperations():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(no_rot.getShape() == arr.getShape())";

.. _example-slice-length-2:

.. dropdown:: length (np_test_1_all.cpp:7335)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 7325
      :emphasize-lines: 11

      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testStringTruncationStringTypes() {
          std::cout << "========= testStringTruncationStringTypes =======================";
      
          // Test truncation behavior
          str8 small("This string is way too long for 8 characters");
          // std::cout << "Long string in str8: '" << small << "'" << std::endl;
          // std::cout << "Length: " << small.length() << " (max: " << str8::max_size << ")" << std::endl;
      
          str16 medium("This is a medium length string that should be truncated");
          // std::cout << "Medium string in str16: '" << medium << "'" << std::endl;
          // std::cout << "Length: " << medium.length() << " (max: " << str16::max_size << ")" << std::endl;
      
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testStringComparisonsStringTypes() {
          std::cout << "========= testStringComparisonsStringTypes =======================";

.. _example-slice-range-3:

.. dropdown:: range (np_test_1_all.cpp:9254)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 9244
      :emphasize-lines: 11

              std::string description = std::string("testNullCharacterHandlingVariableStrings():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(!unicode_null_str.empty())";
              std::cout << std::string("[FAIL] ") + description << std::endl;
              throw std::runtime_error(description);
          }
          std::cout << " -> tests passed" << std::endl;
      }
      
      void testUTF8BoundariesVariableStrings() {
          std::cout << "========= testUTF8BoundariesVariableStrings =======================";
      
          // Test ASCII range (0x00-0x7F)
          vunicode_ ascii_min("\x01");  // Skip NULL for this test
          vunicode_ ascii_max("\x7F");
          if (!(ascii_min.char_count() == 1)) {
              std::string description = std::string("testUTF8BoundariesVariableStrings():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(ascii_min.char_count() == 1)";
              std::cout << std::string("[FAIL] ") + description << std::endl;
              throw std::runtime_error(description);
          }
          if (!(ascii_max.char_count() == 1)) {
              std::string description = std::string("testUTF8BoundariesVariableStrings():") + __FILE__ + ":" + std::to_string(__LINE__) + ": !(ascii_max.char_count() == 1)";
              std::cout << std::string("[FAIL] ") + description << std::endl;

.. _example-slice-to-4:

.. dropdown:: to (np_test_1_all.cpp:13713)
   :class-title: example-dropdown

   .. code-block:: cpp
      :linenos:
      :lineno-start: 13703
      :emphasize-lines: 11

          // std::cout << "[OK] Complex stride pattern maintains memory sharing";
      
          std::cout << " -> tests passed" << std::endl;
        }
      
        void testStrideWithBroadcasting() {
          std::cout << "========= testStrideWithBroadcasting =======================";
      
          // Test broadcasting with different stride patterns
          auto array1 = createInt32Array({ 3, 4 }, 5);
          auto array2 = createInt32Array({ 4 }, 2);  // Will be broadcast to (1, 4) then (3, 4)
      
          // std::cout << "Array1 (3x4):" << std::endl;
          //array1.printArray();
          // std::cout << "Array1 strides: (" << array1.getStrides()[0] << ", " << array1.getStrides()[1] << ")" << std::endl;
      
          // std::cout << "Array2 (4,):" << std::endl;
          //array2.printArray();
          // std::cout << "Array2 strides: (" << array2.getStrides()[0] << ")" << std::endl;
      
          // This should broadcast array2 to match array1's shape