matplotlib · jklymak · Jan 25, 2023 · Jan 25, 2023 · Jan 25, 2023
diff --git a/doc/sphinxext/redirect_from.py b/doc/sphinxext/redirect_from.py
@@ -112,10 +112,10 @@ def _generate_redirects(app, exception):
         html = HTML_TEMPLATE.format(v=builder.get_relative_uri(k, v))
         if p.is_file():
             if p.read_text() != html:
-                logger.warning(f'A redirect-from directive is trying to '
-                               f'create {p}, but that file already exists '
-                               f'(perhaps you need to run "make clean")')
+                logger.warning('A redirect-from directive is trying to '
+                               'create %s, but that file already exists '
+                               '(perhaps you need to run "make clean")', p)
         else:
-            logger.info(f'making refresh html file: {k} redirect to {v}')
+            logger.info('making refresh html file: %s redirect to %s', k, v)
             p.parent.mkdir(parents=True, exist_ok=True)
             p.write_text(html, encoding='utf-8')
diff --git a/lib/matplotlib/_afm.py b/lib/matplotlib/_afm.py
@@ -154,7 +154,7 @@ def _parse_header(fh):
         try:
             converter = header_converters[key]
         except KeyError:
-            _log.error('Found an unknown keyword in AFM header (was %r)' % key)
+            _log.error("Found an unknown keyword in AFM header (was %r)", key)
             continue
         try:
             d[key] = converter(val)

diff --git a/lib/matplotlib/_mathtext.py b/lib/matplotlib/_mathtext.py
@@ -530,7 +530,7 @@ def _get_glyph(self, fontname, font_class, sym):
         except ValueError:
             uniindex = ord('?')
             found_symbol = False
-            _log.warning(f"No TeX to Unicode mapping for {sym!a}.")
+            _log.warning("No TeX to Unicode mapping for %a.", sym)
 
         fontname, uniindex = self._map_virtual_font(
             fontname, font_class, uniindex)
@@ -576,9 +576,9 @@ def _get_glyph(self, fontname, font_class, sym):
                 if (fontname in ('it', 'regular')
                         and isinstance(self, StixFonts)):
                     return self._get_glyph('rm', font_class, sym)
-                _log.warning(f"Font {new_fontname!r} does not have a glyph "
-                             f"for {sym!a} [U+{uniindex:x}], substituting "
-                             "with a dummy symbol.")
+                _log.warning("Font %r does not have a glyph for %a [U+%x], "
+                             "substituting with a dummy symbol.",
+                             new_fontname, sym, uniindex)
                 font = self._get_font('rm')
                 uniindex = 0xA4  # currency char, for lack of anything better
                 slanted = False

diff --git a/lib/matplotlib/backends/backend_webagg_core.py b/lib/matplotlib/backends/backend_webagg_core.py
@@ -266,7 +266,7 @@ def handle_event(self, event):
         return handler(event)
 
     def handle_unknown_event(self, event):
-        _log.warning(f'Unhandled message type {event["type"]}. {event}')
+        _log.warning('Unhandled message type %s. %s', event["type"], event)
 
     def handle_ack(self, event):
         # Network latency tends to decrease if traffic is flowing

diff --git a/lib/matplotlib/font_manager.py b/lib/matplotlib/font_manager.py
@@ -958,7 +958,7 @@ def json_dump(data, filename):
         try:
             json.dump(data, fh, cls=_JSONEncoder, indent=2)
         except OSError as e:
-            _log.warning(f'Could not save font_manager cache {e}')
+            _log.warning('Could not save font_manager cache %s', e)
 
 
 def json_load(filename):