DOC: Correct grammatical issues especially on a/an usage (matplotlib#30736)

* DOC: Correct grammatical issues especially a/an usage

* DOC: Revise the print message

Author: star1327p

lib/matplotlib/axes/_axes.py

@@ -5271,7 +5271,7 @@ def scatter(self, x, y, s=None, c=None, marker=None, cmap=None, norm=None,
         if not marker_obj.is_filled():
             if orig_edgecolor is not None:
                 _api.warn_external(
-                    f"You passed a edgecolor/edgecolors ({orig_edgecolor!r}) "
+                    f"You passed an edgecolor/edgecolors ({orig_edgecolor!r}) "
                     f"for an unfilled marker ({marker!r}).  Matplotlib is "
                     "ignoring the edgecolor in favor of the facecolor.  This "
                     "behavior may change in the future."

lib/matplotlib/mlab.py

@@ -353,7 +353,7 @@ def _spectral_helper(x, y=None, NFFT=None, Fs=None, detrend_func=None,
         # the sampling frequency, if desired. Scale everything, except the DC
         # component and the NFFT/2 component:
 
-        # if we have a even number of frequencies, don't scale NFFT/2
+        # if we have an even number of frequencies, don't scale NFFT/2
         if not NFFT % 2:
             slc = slice(1, -1, None)
         # if we have an odd number, just don't scale DC

lib/matplotlib/tests/test_axes.py

@@ -9104,7 +9104,7 @@ def test_patch_bounds():  # PR 19078
 @mpl.style.context('default')
 def test_warn_ignored_scatter_kwargs():
     with pytest.warns(UserWarning,
-                      match=r"You passed a edgecolor/edgecolors"):
+                      match=r"You passed an edgecolor/edgecolors"):
         plt.scatter([0], [0], marker="+", s=500, facecolor="r", edgecolor="b")
 
 

src/_image_resample.h

@@ -496,7 +496,7 @@ typedef enum {
 } interpolation_e;
 
 
-// T is rgba if and only if it has an T::r field.
+// T is rgba if and only if it has a T::r field.
 template<typename T, typename = void> struct is_grayscale : std::true_type {};
 template<typename T> struct is_grayscale<T, std::void_t<decltype(T::r)>> : std::false_type {};
 template<typename T> constexpr bool is_grayscale_v = is_grayscale<T>::value;

src/tri/_tri.h

@@ -75,7 +75,7 @@
 namespace py = pybind11;
 
 
-/* An edge of a triangle consisting of an triangle index in the range 0 to
+/* An edge of a triangle consisting of a triangle index in the range 0 to
  * ntri-1 and an edge index in the range 0 to 2.  Edge i goes from the
  * triangle's point i to point (i+1)%3. */
 struct TriEdge final