DOC: add small comments

jklymak · jklymak · commit 7c994b8eda1f · 2018-07-03T16:29:35.000-07:00
diff --git a/lib/matplotlib/dates.py b/lib/matplotlib/dates.py
@@ -1235,6 +1235,9 @@ def __init__(self, tz=None, minticks=5, maxticks=None,
                             5000, 10000, 20000, 50000, 100000, 200000, 500000,
                             1000000]}
         if interval_multiples:
+            # Swap "3" for "4" in the DAILY list; If we use 3 we get bad
+            # tick loc for months w/ 31 days: 1, 4,..., 28, 31, 1
+            # If we use 4 then we get: 1, 5, ... 25, 29, 1
             self.intervald[DAILY] = [1, 2, 4, 7, 14, 21]
 
         self._byranges = [None, range(1, 13), range(1, 32),
@@ -1341,8 +1344,9 @@ def get_locator(self, dmin, dmax):
             self._freq = freq
 
             if self._byranges[i] and self.interval_multiples:
-                if i == 2 and interval == 14:
-                        byranges[i] = [1, 15]
+                if i == DAILY and interval == 14:
+                    # just make first and 15th.  Avoids 30th.
+                    byranges[i] = [1, 15]
                 else:
                     byranges[i] = self._byranges[i][::interval]
                 interval = 1
