Merge pull request #2350 from gabrieldemarmiesse/test_working_with_numpy_2

Adding tests for "working with numpy" part 2

docs/examples/tutorial/numpy/convolve2.pyx

+# tag: numpy
+# You can ignore the previous line.
+# It's for internal testing of the cython documentation.
+
+from __future__ import division
+import numpy as np
+# "cimport" is used to import special compile-time information
+# about the numpy module (this is stored in a file numpy.pxd which is
+# currently part of the Cython distribution).
+cimport numpy as np
+
+# We now need to fix a datatype for our arrays. I've used the variable
+# DTYPE for this, which is assigned to the usual NumPy runtime
+# type info object.
+DTYPE = np.int
+# "ctypedef" assigns a corresponding compile-time type to DTYPE_t. For
+# every type in the numpy module there's a corresponding compile-time
+# type with a _t-suffix.
+ctypedef np.int_t DTYPE_t
+# "def" can type its arguments but not have a return type. The type of the
+# arguments for a "def" function is checked at run-time when entering the
+# function.
+#
+# The arrays f, g and h is typed as "np.ndarray" instances. The only effect
+# this has is to a) insert checks that the function arguments really are
+# NumPy arrays, and b) make some attribute access like f.shape[0] much
+# more efficient. (In this example this doesn't matter though.)
+def naive_convolve(np.ndarray f, np.ndarray g):
+    if g.shape[0] % 2 != 1 or g.shape[1] % 2 != 1:
+        raise ValueError("Only odd dimensions on filter supported")
+    assert f.dtype == DTYPE and g.dtype == DTYPE
+    # The "cdef" keyword is also used within functions to type variables. It
+    # can only be used at the top indentation level (there are non-trivial
+    # problems with allowing them in other places, though we'd love to see
+    # good and thought out proposals for it).
+    #
+    # For the indices, the "int" type is used. This corresponds to a C int,
+    # other C types (like "unsigned int") could have been used instead.
+    # Purists could use "Py_ssize_t" which is the proper Python type for
+    # array indices.
+    cdef int vmax = f.shape[0]
+    cdef int wmax = f.shape[1]
+    cdef int smax = g.shape[0]
+    cdef int tmax = g.shape[1]
+    cdef int smid = smax // 2
+    cdef int tmid = tmax // 2
+    cdef int xmax = vmax + 2 * smid
+    cdef int ymax = wmax + 2 * tmid
+    cdef np.ndarray h = np.zeros([xmax, ymax], dtype=DTYPE)
+    cdef int x, y, s, t, v, w
+    # It is very important to type ALL your variables. You do not get any
+    # warnings if not, only much slower code (they are implicitly typed as
+    # Python objects).
+    cdef int s_from, s_to, t_from, t_to
+    # For the value variable, we want to use the same data type as is
+    # stored in the array, so we use "DTYPE_t" as defined above.
+    # NB! An important side-effect of this is that if "value" overflows its
+    # datatype size, it will simply wrap around like in C, rather than raise
+    # an error like in Python.
+    cdef DTYPE_t value
+    for x in range(xmax):
+        for y in range(ymax):
+            s_from = max(smid - x, -smid)
+            s_to = min((xmax - x) - smid, smid + 1)
+            t_from = max(tmid - y, -tmid)
+            t_to = min((ymax - y) - tmid, tmid + 1)
+            value = 0
+            for s in range(s_from, s_to):
+                for t in range(t_from, t_to):
+                    v = x - smid + s
+                    w = y - tmid + t
+                    value += g[smid - s, tmid - t] * f[v, w]
+            h[x, y] = value
+    return h

docs/src/tutorial/numpy.rst

@@ -62,77 +62,9 @@ Adding types
 =============
 
 To add types we use custom Cython syntax, so we are now breaking Python source
-compatibility. Consider this code (*read the comments!*) ::
-
-    from __future__ import division
-    import numpy as np
-    # "cimport" is used to import special compile-time information
-    # about the numpy module (this is stored in a file numpy.pxd which is
-    # currently part of the Cython distribution).
-    cimport numpy as np
-    # We now need to fix a datatype for our arrays. I've used the variable
-    # DTYPE for this, which is assigned to the usual NumPy runtime
-    # type info object.
-    DTYPE = np.int
-    # "ctypedef" assigns a corresponding compile-time type to DTYPE_t. For
-    # every type in the numpy module there's a corresponding compile-time
-    # type with a _t-suffix.
-    ctypedef np.int_t DTYPE_t
-    # "def" can type its arguments but not have a return type. The type of the
-    # arguments for a "def" function is checked at run-time when entering the
-    # function.
-    #
-    # The arrays f, g and h is typed as "np.ndarray" instances. The only effect
-    # this has is to a) insert checks that the function arguments really are
-    # NumPy arrays, and b) make some attribute access like f.shape[0] much
-    # more efficient. (In this example this doesn't matter though.)
-    def naive_convolve(np.ndarray f, np.ndarray g):
-        if g.shape[0] % 2 != 1 or g.shape[1] % 2 != 1:
-            raise ValueError("Only odd dimensions on filter supported")
-        assert f.dtype == DTYPE and g.dtype == DTYPE
-        # The "cdef" keyword is also used within functions to type variables. It
-        # can only be used at the top indentation level (there are non-trivial
-        # problems with allowing them in other places, though we'd love to see
-        # good and thought out proposals for it).
-        #
-        # For the indices, the "int" type is used. This corresponds to a C int,
-        # other C types (like "unsigned int") could have been used instead.
-        # Purists could use "Py_ssize_t" which is the proper Python type for
-        # array indices.
-        cdef int vmax = f.shape[0]
-        cdef int wmax = f.shape[1]
-        cdef int smax = g.shape[0]
-        cdef int tmax = g.shape[1]
-        cdef int smid = smax // 2
-        cdef int tmid = tmax // 2
-        cdef int xmax = vmax + 2*smid
-        cdef int ymax = wmax + 2*tmid
-        cdef np.ndarray h = np.zeros([xmax, ymax], dtype=DTYPE)
-        cdef int x, y, s, t, v, w
-        # It is very important to type ALL your variables. You do not get any
-        # warnings if not, only much slower code (they are implicitly typed as
-        # Python objects).
-        cdef int s_from, s_to, t_from, t_to
-        # For the value variable, we want to use the same data type as is
-        # stored in the array, so we use "DTYPE_t" as defined above.
-        # NB! An important side-effect of this is that if "value" overflows its
-        # datatype size, it will simply wrap around like in C, rather than raise
-        # an error like in Python.
-        cdef DTYPE_t value
-        for x in range(xmax):
-            for y in range(ymax):
-                s_from = max(smid - x, -smid)
-                s_to = min((xmax - x) - smid, smid + 1)
-                t_from = max(tmid - y, -tmid)
-                t_to = min((ymax - y) - tmid, tmid + 1)
-                value = 0
-                for s in range(s_from, s_to):
-                    for t in range(t_from, t_to):
-                        v = x - smid + s
-                        w = y - tmid + t
-                        value += g[smid - s, tmid - t] * f[v, w]
-                h[x, y] = value
-        return h
+compatibility. Consider this code (*read the comments!*) :
+
+.. literalinclude:: ../../examples/tutorial/numpy/convolve2.pyx
 
 After building this and continuing my (very informal) benchmarks, I get: