diff --git a/python/test/cross_validation_test.py b/python/test/cross_validation_test.py
index 0be71bd8b..525e6c8e8 100644
--- a/python/test/cross_validation_test.py
+++ b/python/test/cross_validation_test.py
@@ -138,8 +138,8 @@ def test_sample_model_param_list(self):
             {'n_estimators': 50, 'norm_type': 'clip_0to1', 'random_state': 0},
             {'n_estimators': 10, 'norm_type': 'normalize', 'random_state': 0},
         ]
-        for dict, expected_dict in zip(dicts, expected_dicts):
-            self.assertDictEqual(dict, expected_dict)
+        for actual_dict, expected_dict in zip(dicts, expected_dicts):
+            self.assertDictEqual(actual_dict, expected_dict)
 
         model_param_search_range = {'norm_type': ['normalize', 'clip_0to1'],
                                     'n_estimators': {'low': 10, 'high': 50, 'decimal': 0},
@@ -163,11 +163,11 @@ def test_find_most_frequent_dict(self):
          {'norm_type': 'clip_0to1', 'n_estimators': 50, 'random_state': 0},
         ]
 
-        dict, count = ModelCrossValidation._find_most_frequent_dict(dicts)
+        actual_dict, count = ModelCrossValidation._find_most_frequent_dict(dicts)
         expected_dict = {'norm_type': 'clip_0to1', 'n_estimators': 50, 'random_state': 0}
         expected_count = 2
 
-        self.assertEqual(dict, expected_dict)
+        self.assertEqual(actual_dict, expected_dict)
         self.assertEqual(count, expected_count)
 
     def test_run_nested_kfold_cross_validation_randomforest(self):
diff --git a/python/vmaf/__init__.py b/python/vmaf/__init__.py
index 5057b1447..9158397e2 100644
--- a/python/vmaf/__init__.py
+++ b/python/vmaf/__init__.py
@@ -56,17 +56,17 @@ def project_path(relative_path):
 
 def required(path):
     if not os.path.exists(path):
-        raise AssertionError("%s does not exist, did you build?" % (path))
+        raise AssertionError(f"{path} does not exist, did you build?")
     return path
 
 
 def convert_pixel_format_ffmpeg2vmafexec(ffmpeg_pix_fmt):
-    '''
+    """
     Convert FFmpeg-style pixel format (pix_fmt) to vmaf style.
 
     :param ffmpeg_pix_fmt: FFmpeg-style pixel format, for example: yuv420p, yuv420p10le
     :return: (pixel_format: str, bitdepth: int), for example: (420, 8), (420, 10)
-    '''
+    """
     assert ffmpeg_pix_fmt in ['yuv420p', 'yuv422p', 'yuv444p',
                               'yuv420p10le', 'yuv422p10le', 'yuv444p10le',
                               'yuv420p12le', 'yuv422p12le', 'yuv444p12le',
diff --git a/python/vmaf/config.py b/python/vmaf/config.py
index 6c6ca8b7d..4d3481931 100644
--- a/python/vmaf/config.py
+++ b/python/vmaf/config.py
@@ -224,11 +224,11 @@ class DisplayConfig(object):
     def show(**kwargs):
         from vmaf import plt
         if 'write_to_dir' in kwargs:
-            format = kwargs['format'] if 'format' in kwargs else 'png'
+            fmt = kwargs['format'] if 'format' in kwargs else 'png'
             filedir = kwargs['write_to_dir'] if kwargs['write_to_dir'] is not None else VmafConfig.workspace_path('output')
             os.makedirs(filedir, exist_ok=True)
             for fignum in plt.get_fignums():
                 fig = plt.figure(fignum)
-                fig.savefig(os.path.join(filedir, str(fignum) + '.' + format), format=format)
+                fig.savefig(os.path.join(filedir, str(fignum) + '.' + fmt), format=fmt)
         else:
             plt.show()
diff --git a/python/vmaf/core/nn_train_test_model.py b/python/vmaf/core/nn_train_test_model.py
index dc65b65dd..d43e1fd70 100644
--- a/python/vmaf/core/nn_train_test_model.py
+++ b/python/vmaf/core/nn_train_test_model.py
@@ -240,9 +240,9 @@ def _populate_patches_and_labels(self, xkeys, xys, mode='train'):
                 jv = jv[idx]
 
                 patches_found = 0
-                for (y, x) in zip(iv, jv):
-                    patches_cache[patch_idx] = img[y: y + self.patch_height,
-                                                   x: x + self.patch_width]
+                for (yy, xx) in zip(iv, jv):
+                    patches_cache[patch_idx] = img[yy: yy + self.patch_height,
+                                                   xx: xx + self.patch_width]
                     if mode == 'train':
                         labels_cache[patch_idx] = label
 
diff --git a/python/vmaf/core/quality_runner.py b/python/vmaf/core/quality_runner.py
index 456f77d5b..c2a3bd348 100644
--- a/python/vmaf/core/quality_runner.py
+++ b/python/vmaf/core/quality_runner.py
@@ -1219,8 +1219,7 @@ def _generate_result(self, asset):
             if use_default_built_in_model:
                 models = []
         else:
-            model0 = []
-            model0.append(f'name=vmaf')
+            model0 = ['name=vmaf']
 
             if self.optional_dict is not None and 'model_filepath' in self.optional_dict:
                 model_filepath = self.optional_dict['model_filepath']
diff --git a/python/vmaf/routine.py b/python/vmaf/routine.py
index 92f99cbd7..f283c17bd 100644
--- a/python/vmaf/routine.py
+++ b/python/vmaf/routine.py
@@ -391,7 +391,7 @@ def run_test_on_dataset(test_dataset, runner_class, ax,
         for test_asset in test_assets:
             assert test_asset.groundtruth is not None
     except AssertionError:
-        # no groundtruth, try do subjective modeling
+        # no groundtruth, try to do subjective modeling
         from sureal.dataset_reader import RawDatasetReader
         from sureal.subjective_model import DmosModel
         subj_model_class = kwargs['subj_model_class'] if 'subj_model_class' in kwargs and kwargs['subj_model_class'] is not None else DmosModel
@@ -548,11 +548,11 @@ def run_test_on_dataset(test_dataset, runner_class, ax,
 
 
 def print_matplotlib_warning():
-    print("Warning: cannot import matplotlib, no picture displayed. " \
-          "If you are on Mac OS and have installed matplotlib, you " \
-          "possibly need to run: \nsudo pip uninstall python-dateutil \n" \
-          "sudo pip install python-dateutil==2.2 \n" \
-          "Refer to: http://stackoverflow.com/questions/27630114/matplotlib-issue-on-os-x-importerror-cannot-import-name-thread")
+    print("Warning: cannot import matplotlib, no picture displayed. "
+          "If you are on Mac OS and have installed matplotlib, you "
+          "possibly need to run: \nsudo pip uninstall python-dateutil \n"
+          "sudo pip install python-dateutil==2.2 \n"
+          "Refer to: https://stackoverflow.com/questions/27630114/matplotlib-issue-on-os-x-importerror-cannot-import-name-thread")
 
 
 def train_test_vmaf_on_dataset(train_dataset, test_dataset,
@@ -569,7 +569,7 @@ def train_test_vmaf_on_dataset(train_dataset, test_dataset,
         for train_asset in train_assets:
             assert train_asset.groundtruth is not None
     except AssertionError:
-        # no groundtruth, try do subjective modeling
+        # no groundtruth, try to do subjective modeling
         from sureal.dataset_reader import RawDatasetReader
         from sureal.subjective_model import DmosModel
         subj_model_class = kwargs['subj_model_class'] if 'subj_model_class' in kwargs and kwargs['subj_model_class'] is not None else DmosModel
@@ -684,7 +684,7 @@ def train_test_vmaf_on_dataset(train_dataset, test_dataset,
             for test_asset in test_assets:
                 assert test_asset.groundtruth is not None
         except AssertionError:
-            # no groundtruth, try do subjective modeling
+            # no groundtruth, try to do subjective modeling
             from sureal.dataset_reader import RawDatasetReader
             from sureal.subjective_model import DmosModel
             subj_model_class = kwargs['subj_model_class'] if 'subj_model_class' in kwargs and kwargs['subj_model_class'] is not None else DmosModel
diff --git a/python/vmaf/tools/decorator.py b/python/vmaf/tools/decorator.py
index 0f59e06ec..83cfa2583 100644
--- a/python/vmaf/tools/decorator.py
+++ b/python/vmaf/tools/decorator.py
@@ -14,7 +14,7 @@
 def deprecated(func):
     """
     Mark a function as deprecated.
-    It will result in a warning being emmitted when the function is used.
+    It will result in a warning being emitted when the function is used.
     """
 
     def new_func(*args, **kwargs):
diff --git a/python/vmaf/tools/interpolation_utils.py b/python/vmaf/tools/interpolation_utils.py
index 66b665ed8..ba7d1381c 100644
--- a/python/vmaf/tools/interpolation_utils.py
+++ b/python/vmaf/tools/interpolation_utils.py
@@ -35,7 +35,7 @@ def interpolateRateFromMetric(cls, rdPointsList, arrayDistInLogScale):
             yk = log_rate[0]
             segmentOfInterest = 0
             for i in range(N-1):
-                if log_dist[i] <= distInLogScale and log_dist[i+1] >= distInLogScale:
+                if log_dist[i] <= distInLogScale <= log_dist[i + 1]:
                     distBegin = log_dist[i]
                     yk = log_rate[i]
                     segmentOfInterest = i
@@ -72,7 +72,7 @@ def computeParamsForSegments(cls, rdPointsList, log_rate, log_dist, H, delta, d,
         N = len(rdPointsList)
 
         for i in range(N):
-            if (convertRateUsingLogarithm):
+            if convertRateUsingLogarithm:
                 log_rate.append(np.log10(rdPointsList[i][0]))
             else:
                 log_rate.append(rdPointsList[i][0])
diff --git a/python/vmaf/tools/misc.py b/python/vmaf/tools/misc.py
index 41bb2e850..dc82f07d5 100644
--- a/python/vmaf/tools/misc.py
+++ b/python/vmaf/tools/misc.py
@@ -84,7 +84,7 @@ def get_file_name_with_extension(path):
 
 
 def get_file_name_extension(path):
-    '''
+    """
     >>> get_file_name_extension("file:///mnt/zli/test.txt")
     'txt'
     >>> get_file_name_extension("test.txt")
@@ -93,7 +93,7 @@ def get_file_name_extension(path):
     ''
     >>> get_file_name_extension("test.265")
     '265'
-    '''
+    """
     return Path(path).suffix[1:]
 
 
@@ -118,9 +118,9 @@ def make_parent_dirs_if_nonexist(path):
     os.makedirs(dst_dir, exist_ok=True)
 
 
-def delete_dir_if_exists(dir):
-    if os.path.isdir(dir):
-        os.rmdir(dir)
+def delete_dir_if_exists(dir_to_delete):
+    if os.path.isdir(dir_to_delete):
+        os.rmdir(dir_to_delete)
 
 
 def get_normalized_string_from_dict(d):
@@ -174,7 +174,7 @@ def indices(a, func):
     [2, 3]
     >>> indices([1, 2, 3, 4], lambda x: x==2.5)
     []
-    >>> indices([1, 2, 3, 4], lambda x: x>1 and x<=3)
+    >>> indices([1, 2, 3, 4], lambda x: 1 < x <= 3)
     [1, 2]
     >>> indices([1, 2, 3, 4], lambda x: x in [2, 4])
     [1, 3]
@@ -250,7 +250,7 @@ def empty_object():
 
 
 def get_cmd_option(argv, begin, end, option):
-    '''
+    """
 
     >>> get_cmd_option(['a', 'b', 'c', '--xyz', '123'], 3, 5, '--xyz')
     '123'
@@ -264,7 +264,7 @@ def get_cmd_option(argv, begin, end, option):
     >>> get_cmd_option(['a', 'b', 'c', '--xyz', '123'], 0, 5, 'b')
     'c'
 
-    '''
+    """
     itr = None
     for itr in range(begin, end):
         if argv[itr] == option:
@@ -275,7 +275,7 @@ def get_cmd_option(argv, begin, end, option):
 
 
 def cmd_option_exists(argv, begin, end, option):
-    '''
+    """
 
     >>> cmd_option_exists(['a', 'b', 'c', 'd'], 2, 4, 'c')
     True
@@ -288,7 +288,7 @@ def cmd_option_exists(argv, begin, end, option):
     >>> cmd_option_exists(['a', 'b', 'c', 'd'], 2, 4, 'b')
     False
 
-    '''
+    """
     found = False
     for itr in range(begin, end):
         if argv[itr] == option:
@@ -298,12 +298,12 @@ def cmd_option_exists(argv, begin, end, option):
 
 
 def index_and_value_of_min(l):
-    '''
+    """
 
     >>> index_and_value_of_min([2, 0, 3])
     (1, 0)
 
-    '''
+    """
     return min(enumerate(l), key=lambda x: x[1])
 
 
@@ -348,7 +348,7 @@ def func_wrapper(idx_args):
             if not p.is_alive():
                 active_procs.remove(p)
 
-        # check if can add a proc to active_procs (add gradually one per loop)
+        # check if we can add a proc to active_procs (add gradually one per loop)
         if len(active_procs) < max_active_procs and len(waiting_procs) > 0:
             # move one proc from waiting_procs to active_procs
             p = waiting_procs.pop()
@@ -367,7 +367,7 @@ def func_wrapper(idx_args):
 
 
 def check_program_exist(program):
-    '''
+    """
 
     >>> check_program_exist("xxxafasd34df")
     False
@@ -380,7 +380,7 @@ def check_program_exist(program):
     >>> check_program_exist("pwd")
     True
 
-    '''
+    """
     try:
         with open(os.devnull, "wb") as devnull_fd:
             subprocess.call(program.split(), stdout=devnull_fd)
@@ -394,7 +394,7 @@ def check_program_exist(program):
 
 
 def check_scanf_match(string, template):
-    '''
+    """
     >>> check_scanf_match('frame00000000.icpf', 'frame%08d.icpf')
     True
     >>> check_scanf_match('frame00000003.icpf', 'frame%08d.icpf')
@@ -419,8 +419,7 @@ def check_scanf_match(string, template):
     True
     >>> check_scanf_match('/mnt/hgfs/ZLI-NFLX-10/USCJND/ref/1920x1080/videoSRC001_1920x1080_30.yuv.avi', '/mnt/hgfs/ZLI-NFLX-10/USCJND/ref/1920x1080/videoSRC001_1920x1080_*.yuv.avi')
     True
-    '''
-    ret = False
+    """
     try:
         sscanf(string, template)
         return True