replace most `str.format` calls with f-strings

examples/compare_ashs_freesurfer_hipposf.ipynb

@@ -1280,7 +1280,7 @@
     "                     y='volume_mm^3',\n",
     "                     hue='segmentation_mode')\n",
     "ax.set_xticklabels(ax.get_xticklabels(), rotation=60)\n",
-    "ax.set_title('Hippocampal Subfield Volumes of Subject {}'.format(SUBJECT));"
+    "ax.set_title(f'Hippocampal Subfield Volumes of Subject {SUBJECT}');"
    ]
   }
  ],

examples/freesurfer_hipposf.ipynb

@@ -235,7 +235,7 @@
     "\n",
     "volume_frame['segmentation_mode'] = volume_frame.apply(generate_mode_label, axis=1)\n",
     "volume_frame.sort_values(by=['subfield', 'segmentation_mode']) \\\n",
-    "    .to_csv('freesurfer_hipposf_volumes_{}.csv'.format(SUBJECT), index=False)\n",
+    "    .to_csv(f'freesurfer_hipposf_volumes_{SUBJECT}.csv', index=False)\n",
     "volume_frame['segmentation_mode'].value_counts().sort_index()"
    ]
   },
@@ -1195,7 +1195,7 @@
     "                     x='hemisphere',\n",
     "                     y='volume_mm^3',\n",
     "                     hue='segmentation_mode')\n",
-    "ax.set_title('Hippocampal Volume of Subject {}'.format(SUBJECT))\n",
+    "ax.set_title(f'Hippocampal Volume of Subject {SUBJECT}')\n",
     "ax.legend(loc='lower right');"
    ]
   },
@@ -2007,7 +2007,7 @@
     "                     y='volume_mm^3',\n",
     "                     hue='segmentation_mode')\n",
     "ax.set_xticklabels(ax.get_xticklabels(), rotation=60)\n",
-    "ax.set_title('Hippocampal Subfield Volumes of Subject {}\\nLeft Hemisphere'.format(SUBJECT));"
+    "ax.set_title(f'Hippocampal Subfield Volumes of Subject {SUBJECT}\\nLeft Hemisphere');"
    ]
   }
  ],

freesurfer_volume_reader/__main__.py

@@ -49,8 +49,8 @@ def main():
     )
     for source_type, file_class in VOLUME_FILE_FINDERS.items():
         argparser.add_argument(
-            "--{}-filename-regex".format(source_type),
-            dest="filename_regex.{}".format(source_type),
+            f"--{source_type}-filename-regex",
+            dest=f"filename_regex.{source_type}",
             metavar="REGULAR_EXPRESSION",
             type=re.compile,
             default=remove_group_names_from_regex(file_class.FILENAME_PATTERN),
@@ -65,7 +65,7 @@ def main():
         metavar="ROOT_DIR",
         nargs="*" if subjects_dir_path else "+",
         default=[subjects_dir_path],
-        help="default: $SUBJECTS_DIR ({})".format(subjects_dir_path),
+        help=f"default: $SUBJECTS_DIR ({subjects_dir_path})",
     )
     argparser.add_argument("--version", action="version", version=__version__)
     args = argparser.parse_args()