feat: added grayscale function

Author: ForNeus57

Makefile

@@ -5,4 +5,4 @@ python-install:
 	pip3 install .
 
 python-install-editable:
-	pip3 install -e .[development]
+	pip3 install -e .[development]

src/app/fast/foo.c

@@ -2,84 +2,103 @@
 #include <Python.h>
 #include <numpy/arrayobject.h>
 
-static PyObject *
-spam_system(PyObject *self, PyObject *args)
-{
-    const char *command;
-    int sts;
-
-    if (!PyArg_ParseTuple(args, "s", &command))
-        return NULL;
-    sts = system(command);
-    return PyLong_FromLong(sts);
-}
-
 static PyObject * 
-numpy_add(PyObject *self, PyObject *args){
+numpy_grayscale(PyObject *self, PyObject *args){
     PyArrayObject *arr;
     PyArg_ParseTuple(args, "O", &arr);
     if(PyErr_Occurred()){
         return NULL;
     }
+
     if(!PyArray_Check(arr) || PyArray_TYPE(arr) != NPY_DOUBLE) {
         PyErr_SetString(PyExc_TypeError, "Argument must be a numpy array of type double!");
         return NULL;
     }
+    Py_INCREF(arr);
+
+//    PyObject* arr_copy = (PyArrayObject *)PyArray_NewCopy(arr, NPY_CORDER);
+
+    int src_nd = PyArray_NDIM(arr);
+    if (src_nd != 3) {
+        PyErr_SetString(PyExc_TypeError, "Array number of dimensions must be equal to 3");
+        return NULL;
+    }
+
+    npy_intp* src_shape = PyArray_SIZE(arr);
+    if (src_shape[2] != 3) {
+        PyErr_SetString(PyExc_TypeError, "Array number of must have 3 channels for colors");
+        return NULL;
+    }
+
+    npy_intp result[2] = {src_shape[0], src_shape[1]};
 
+    PyArrayObject *new_array = (PyArrayObject *)PyArray_SimpleNew(src_nd - 1, result, NPY_DOUBLE);
+
+    Py_DECREF(arr);
 
     double *data = PyArray_DATA(arr);
     int64_t size = PyArray_SIZE(arr);
 
-    double total=0;
-    for (int i=0; i < size; i++){
-        total += data[i];
+    double* new_data = PyArray_DATA(new_array);
+    for (int i = 0; i < src_shape[0]; i++)
+    {
+        for (int j = 0; j < src_shape[1]; ++j)
+        {
+            for (int k = 0; k < src_shape[2]; ++k)
+            {
+                new_data[i * src_shape[1] + j] = (
+                    data[i * src_shape[1] * src_shape[2] + j * src_shape[2] + 0]
+                    + data[i * src_shape[1] * src_shape[2] + j * src_shape[2] + 1]
+                    + data[i * src_shape[1] * src_shape[2] + j * src_shape[2] + 2]
+                ) / 3;
+            }
+        }
     }
-    return PyFloat_FromDouble(total);
+
+    return new_array;
 }
 
 static PyObject *SpamError = NULL;
 
 static int
-spam_module_exec(PyObject *m)
+fast_module_exec(PyObject *m)
 {
     if (SpamError != NULL) {
         PyErr_SetString(PyExc_ImportError,
-                        "cannot initialize spam module more than once");
+                        "cannot initialize fast module more than once");
         return -1;
     }
-    SpamError = PyErr_NewException("spam.error", NULL, NULL);
+    SpamError = PyErr_NewException("fast.error", NULL, NULL);
     if (PyModule_AddObjectRef(m, "SpamError", SpamError) < 0) {
         return -1;
     }
 
     return 0;
 }
 
-static PyMethodDef spam_methods[] = {
-    {"system",  spam_system, METH_VARARGS,
-     "Execute a shell command."},
-     {"numpy_add", numpy_add, METH_VARARGS,
-    "Perform adding operation."},
+static PyMethodDef fast_methods[] = {
+     {"grayscale", numpy_grayscale, METH_VARARGS,
+    "Perform grayscale operation, return copy."},
     {NULL, NULL, 0, NULL}        /* Sentinel */
 };
 
-static PyModuleDef_Slot spam_module_slots[] = {
-    {Py_mod_exec, spam_module_exec},
+static PyModuleDef_Slot fast_module_slots[] = {
+    {Py_mod_exec, fast_module_exec},
     {0, NULL}
 };
 
-static struct PyModuleDef spam_module = {
+static struct PyModuleDef fast_module = {
     .m_base = PyModuleDef_HEAD_INIT,
-    .m_name = "spam",
+    .m_name = "fast",
     .m_size = 0,  // non-negative
-    .m_slots = spam_module_slots,
-    .m_methods = spam_methods
+    .m_slots = fast_module_slots,
+    .m_methods = fast_methods
 };
 
 PyMODINIT_FUNC
 PyInit_fast(void)
 {
-    PyObject* module_obj = PyModuleDef_Init(&spam_module);
+    PyObject* module_obj = PyModuleDef_Init(&fast_module);
     import_array();
     return module_obj;
 }