matplotlib
diff --git a/‎lib/matplotlib/font_manager.py
Copy file name to clipboardExpand all lines: lib/matplotlib/font_manager.py
+24-14Lines changed: 24 additions & 14 deletions b/‎lib/matplotlib/font_manager.py
Copy file name to clipboardExpand all lines: lib/matplotlib/font_manager.py
+24-14Lines changed: 24 additions & 14 deletions
@@ -1011,7 +1011,7 @@ class FontManager:
     # Increment this version number whenever the font cache data
     # format or behavior has changed and requires an existing font
     # cache files to be rebuilt.
-    __version__ = 330
+    __version__ = 335
 
     def __init__(self, size=None, weight='normal'):
         self._version = self.__version__
@@ -1031,6 +1031,9 @@ def __init__(self, size=None, weight='normal'):
         self.afmlist = []
         self.ttflist = []
 
+        # keep track of fonts
+        self._not_found = {'generic': [], 'family': [], 'fallback': []}
+
         # Delay the warning by 5s.
         timer = threading.Timer(5, lambda: _log.warning(
             'Matplotlib is building the font cache; this may take a moment.'))
@@ -1049,6 +1052,12 @@ def __init__(self, size=None, weight='normal'):
         finally:
             timer.cancel()
 
+    def _warn_not_found(self, family, warning_id, warning_msg):
+        """Log missing fonts once per warning message"""
+        if family not in self._not_found[warning_id]:
+            _log.warning(warning_msg)
+            self._not_found[warning_id].append(family)
+
     def addfont(self, path):
         """
         Cache the properties of the font at *path* to make it available to the
@@ -1362,13 +1371,14 @@ def _find_fonts_by_props(self, prop, fontext='ttf', directory=None,
                 )
             except ValueError:
                 if family in font_family_aliases:
-                    _log.warning(
-                        "findfont: Generic family %r not found because "
-                        "none of the following families were found: %s",
-                        family, ", ".join(self._expand_aliases(family))
-                    )
+                    msg = (f"findfont: Generic family '{family}' not found because "
+                            "none of the following families were found: "
+                           f"{','.join(self._expand_aliases(family))}")
+                    self._warn_not_found(family, 'generic', msg)
+
                 else:
-                    _log.warning("findfont: Font family %r not found.", family)
+                    msg = f"findfont: Font family '{family}' not found."
+                    self._warn_not_found(family, 'family', msg)
 
         # only add default family if no other font was found and
         # fallback_to_default is enabled
@@ -1429,15 +1439,15 @@ def _findfont_cached(self, prop, fontext, directory, fallback_to_default,
 
         if best_font is None or best_score >= 10.0:
             if fallback_to_default:
-                _log.warning(
-                    'findfont: Font family %s not found. Falling back to %s.',
-                    prop.get_family(), self.defaultFamily[fontext])
+                msg = (f"findfont: Font family {prop.get_family()} not found. "
+                       f"Falling back to {self.defaultFamily[fontext]}.")
+                self._warn_not_found(prop.get_family(), 'fallback', msg)
                 for family in map(str.lower, prop.get_family()):
                     if family in font_family_aliases:
-                        _log.warning(
-                            "findfont: Generic family %r not found because "
-                            "none of the following families were found: %s",
-                            family, ", ".join(self._expand_aliases(family)))
+                        msg = (f"findfont: Generic family '{family}' not found because "
+                                "none of the following families were found: "
+                               f"{','.join(self._expand_aliases(family))}")
+                        self._warn_not_found(family, 'generic', msg)
                 default_prop = prop.copy()
                 default_prop.set_family(self.defaultFamily[fontext])
                 return self.findfont(default_prop, fontext, directory,