Replace len() Zero Checks with Pythonic Empty Sequence Checks

examples/spot/lightning_cifar10/train.py

@@ -163,7 +163,7 @@ def main():
     )
 
     model_ckpts = glob.glob(argv.root_dir + "/*.ckpt")
-    if argv.resume and len(model_ckpts) > 0:
+    if argv.resume and model_ckpts:
         latest_ckpt = max(model_ckpts, key=os.path.getctime)
         trainer.fit(model, cifar10_dm, ckpt_path=latest_ckpt)
     else:

format.sh

@@ -132,7 +132,7 @@ elif [[ "$1" == '--all' ]]; then
     pylint "${PYLINT_FLAGS[@]}" sky
 else
     # Pylint only files in sky/ that have changed in last commit.
-    changed_files=$(git diff --name-only --diff-filter=ACM "$MERGEBASE" -- 'sky/*.py' 'sky/*.pyi')
+    changed_files=$(git diff --name-only --diff-filter=ACM "$MERGEBASE" -- 'sky/*.py' 'sky/*.pyi' ':!sky/skylet/**')
     if [[ -n "$changed_files" ]]; then
         echo "$changed_files" | tr '\n' '\0' | xargs -0 pylint "${PYLINT_FLAGS[@]}"
     else

sky/backends/cloud_vm_ray_backend.py

@@ -2578,7 +2578,7 @@ def register_info(self, **kwargs) -> None:
             self._optimize_target) or optimizer.OptimizeTarget.COST
         self._requested_features = kwargs.pop('requested_features',
                                               self._requested_features)
-        assert len(kwargs) == 0, f'Unexpected kwargs: {kwargs}'
+        assert not kwargs, f'Unexpected kwargs: {kwargs}'
 
     def check_resources_fit_cluster(
         self,

sky/check.py

@@ -127,7 +127,7 @@ def get_all_clouds():
             '\nNote: The following clouds were disabled because they were not '
             'included in allowed_clouds in ~/.sky/config.yaml: '
             f'{", ".join([c for c in disallowed_cloud_names])}')
-    if len(all_enabled_clouds) == 0:
+    if not all_enabled_clouds:
         echo(
             click.style(
                 'No cloud is enabled. SkyPilot will not be able to run any '

sky/cli.py

@@ -114,7 +114,7 @@ def _get_glob_clusters(clusters: List[str], silent: bool = False) -> List[str]:
     glob_clusters = []
     for cluster in clusters:
         glob_cluster = global_user_state.get_glob_cluster_names(cluster)
-        if len(glob_cluster) == 0 and not silent:
+        if not glob_cluster and not silent:
             click.echo(f'Cluster {cluster} not found.')
         glob_clusters.extend(glob_cluster)
     return list(set(glob_clusters))
@@ -125,7 +125,7 @@ def _get_glob_storages(storages: List[str]) -> List[str]:
     glob_storages = []
     for storage_object in storages:
         glob_storage = global_user_state.get_glob_storage_name(storage_object)
-        if len(glob_storage) == 0:
+        if not glob_storage:
             click.echo(f'Storage {storage_object} not found.')
         glob_storages.extend(glob_storage)
     return list(set(glob_storages))
@@ -1466,7 +1466,7 @@ def _get_services(service_names: Optional[List[str]],
             if len(service_records) != 1:
                 plural = 's' if len(service_records) > 1 else ''
                 service_num = (str(len(service_records))
-                               if len(service_records) > 0 else 'No')
+                               if service_records else 'No')
                 raise click.UsageError(
                     f'{service_num} service{plural} found. Please specify '
                     'an existing service to show its endpoint. Usage: '
@@ -1689,8 +1689,7 @@ def status(all: bool, refresh: bool, ip: bool, endpoints: bool,
             if len(clusters) != 1:
                 with ux_utils.print_exception_no_traceback():
                     plural = 's' if len(clusters) > 1 else ''
-                    cluster_num = (str(len(clusters))
-                                   if len(clusters) > 0 else 'No')
+                    cluster_num = (str(len(clusters)) if clusters else 'No')
                     cause = 'a single' if len(clusters) > 1 else 'an existing'
                     raise ValueError(
                         _STATUS_PROPERTY_CLUSTER_NUM_ERROR_MESSAGE.format(
@@ -1715,9 +1714,8 @@ def status(all: bool, refresh: bool, ip: bool, endpoints: bool,
                 with ux_utils.print_exception_no_traceback():
                     plural = 's' if len(cluster_records) > 1 else ''
                     cluster_num = (str(len(cluster_records))
-                                   if len(cluster_records) > 0 else
-                                   f'{clusters[0]!r}')
-                    verb = 'found' if len(cluster_records) > 0 else 'not found'
+                                   if cluster_records else f'{clusters[0]!r}')
+                    verb = 'found' if cluster_records else 'not found'
                     cause = 'a single' if len(clusters) > 1 else 'an existing'
                     raise ValueError(
                         _STATUS_PROPERTY_CLUSTER_NUM_ERROR_MESSAGE.format(
@@ -2463,7 +2461,7 @@ def start(
                 '(see `sky status`), or the -a/--all flag.')
 
     if all:
-        if len(clusters) > 0:
+        if clusters:
             click.echo('Both --all and cluster(s) specified for sky start. '
                        'Letting --all take effect.')
 
@@ -2793,7 +2791,7 @@ def _down_or_stop_clusters(
             option_str = '{stop,down}'
         operation = f'{verb} auto{option_str} on'
 
-    if len(names) > 0:
+    if names:
         controllers = [
             name for name in names
             if controller_utils.Controllers.from_name(name) is not None
@@ -2807,7 +2805,7 @@ def _down_or_stop_clusters(
         # Make sure the controllers are explicitly specified without other
         # normal clusters.
         if controllers:
-            if len(names) != 0:
+            if names:
                 names_str = ', '.join(map(repr, names))
                 raise click.UsageError(
                     f'{operation} controller(s) '
@@ -2860,7 +2858,7 @@ def _down_or_stop_clusters(
 
     if apply_to_all:
         all_clusters = global_user_state.get_clusters()
-        if len(names) > 0:
+        if names:
             click.echo(
                 f'Both --all and cluster(s) specified for `sky {command}`. '
                 'Letting --all take effect.')
@@ -2887,7 +2885,7 @@ def _down_or_stop_clusters(
         click.echo('Cluster(s) not found (tip: see `sky status`).')
         return
 
-    if not no_confirm and len(clusters) > 0:
+    if not no_confirm and clusters:
         cluster_str = 'clusters' if len(clusters) > 1 else 'cluster'
         cluster_list = ', '.join(clusters)
         click.confirm(
@@ -2996,7 +2994,7 @@ def check(clouds: Tuple[str], verbose: bool):
       # Check only specific clouds - AWS and GCP.
       sky check aws gcp
     """
-    clouds_arg = clouds if len(clouds) > 0 else None
+    clouds_arg = clouds if clouds else None
     sky_check.check(verbose=verbose, clouds=clouds_arg)
 
 
@@ -3131,7 +3129,7 @@ def _get_kubernetes_realtime_gpu_table(
                                  f'capacity ({list(capacity.keys())}), '
                                  f'and available ({list(available.keys())}) '
                                  'must be same.')
-        if len(counts) == 0:
+        if not counts:
             err_msg = 'No GPUs found in Kubernetes cluster. '
             debug_msg = 'To further debug, run: sky check '
             if name_filter is not None:
@@ -3275,7 +3273,7 @@ def _output():
             for tpu in service_catalog.get_tpus():
                 if tpu in result:
                     tpu_table.add_row([tpu, _list_to_str(result.pop(tpu))])
-            if len(tpu_table.get_string()) > 0:
+            if tpu_table.get_string():
                 yield '\n\n'
             yield from tpu_table.get_string()
 
@@ -3386,7 +3384,7 @@ def _output():
             yield (f'{colorama.Fore.CYAN}{colorama.Style.BRIGHT}'
                    f'Cloud GPUs{colorama.Style.RESET_ALL}\n')
 
-        if len(result) == 0:
+        if not result:
             quantity_str = (f' with requested quantity {quantity}'
                             if quantity else '')
             cloud_str = f' on {cloud_obj}.' if cloud_name else ' in cloud catalogs.'
@@ -3515,7 +3513,7 @@ def storage_delete(names: List[str], all: bool, yes: bool):  # pylint: disable=r
         # Delete all storage objects.
         sky storage delete -a
     """
-    if sum([len(names) > 0, all]) != 1:
+    if sum([bool(names), all]) != 1:
         raise click.UsageError('Either --all or a name must be specified.')
     if all:
         storages = sky.storage_ls()
@@ -3857,8 +3855,8 @@ def jobs_cancel(name: Optional[str], job_ids: Tuple[int], all: bool, yes: bool):
             exit_if_not_accessible=True)
 
     job_id_str = ','.join(map(str, job_ids))
-    if sum([len(job_ids) > 0, name is not None, all]) != 1:
-        argument_str = f'--job-ids {job_id_str}' if len(job_ids) > 0 else ''
+    if sum([bool(job_ids), name is not None, all]) != 1:
+        argument_str = f'--job-ids {job_id_str}' if job_ids else ''
         argument_str += f' --name {name}' if name is not None else ''
         argument_str += ' --all' if all else ''
         raise click.UsageError(
@@ -4490,9 +4488,9 @@ def serve_down(service_names: List[str], all: bool, purge: bool, yes: bool,
         # Forcefully tear down a specific replica, even in failed status.
         sky serve down my-service --replica-id 1 --purge
     """
-    if sum([len(service_names) > 0, all]) != 1:
-        argument_str = f'SERVICE_NAMES={",".join(service_names)}' if len(
-            service_names) > 0 else ''
+    if sum([bool(service_names), all]) != 1:
+        argument_str = (f'SERVICE_NAMES={",".join(service_names)}'
+                        if service_names else '')
         argument_str += ' --all' if all else ''
         raise click.UsageError(
             'Can only specify one of SERVICE_NAMES or --all. '
@@ -4865,7 +4863,7 @@ def benchmark_launch(
     if idle_minutes_to_autostop is None:
         idle_minutes_to_autostop = 5
     commandline_args['idle-minutes-to-autostop'] = idle_minutes_to_autostop
-    if len(env) > 0:
+    if env:
         commandline_args['env'] = [f'{k}={v}' for k, v in env]
 
     # Launch the benchmarking clusters in detach mode in parallel.
@@ -5144,7 +5142,7 @@ def benchmark_delete(benchmarks: Tuple[str], all: Optional[bool],
         raise click.BadParameter(
             'Either specify benchmarks or use --all to delete all benchmarks.')
     to_delete = []
-    if len(benchmarks) > 0:
+    if benchmarks:
         for benchmark in benchmarks:
             record = benchmark_state.get_benchmark_from_name(benchmark)
             if record is None:
@@ -5153,7 +5151,7 @@ def benchmark_delete(benchmarks: Tuple[str], all: Optional[bool],
                 to_delete.append(record)
     if all:
         to_delete = benchmark_state.get_benchmarks()
-        if len(benchmarks) > 0:
+        if benchmarks:
             print('Both --all and benchmark(s) specified '
                   'for sky bench delete. Letting --all take effect.')
 

sky/cloud_stores.py

@@ -133,7 +133,7 @@ def is_directory(self, url: str) -> bool:
         # If <url> is a bucket root, then we only need `gsutil` to succeed
         # to make sure the bucket exists. It is already a directory.
         _, key = data_utils.split_gcs_path(url)
-        if len(key) == 0:
+        if not key:
             return True
         # Otherwise, gsutil ls -d url will return:
         #   --> url.rstrip('/')          if url is not a directory

sky/clouds/gcp.py

@@ -829,7 +829,7 @@ def check_credentials(cls) -> Tuple[bool, Optional[str]]:
         ret_permissions = request.execute().get('permissions', [])
 
         diffs = set(gcp_minimal_permissions).difference(set(ret_permissions))
-        if len(diffs) > 0:
+        if diffs:
             identity_str = identity[0] if identity else None
             return False, (
                 'The following permissions are not enabled for the current '

sky/clouds/kubernetes.py

@@ -136,7 +136,7 @@ def _existing_allowed_contexts(cls) -> List[Optional[str]]:
         use the service account mounted in the pod.
         """
         all_contexts = kubernetes_utils.get_all_kube_config_context_names()
-        if len(all_contexts) == 0:
+        if not all_contexts:
             return []
         if all_contexts == [None]:
             # If only one context is found and it is None, we are running in a

sky/clouds/service_catalog/common.py

@@ -270,7 +270,7 @@ def _get_candidate_str(loc: str, all_loc: List[str]) -> str:
         candidate_loc = difflib.get_close_matches(loc, all_loc, n=5, cutoff=0.9)
         candidate_loc = sorted(candidate_loc)
         candidate_strs = ''
-        if len(candidate_loc) > 0:
+        if candidate_loc:
             candidate_strs = ', '.join(candidate_loc)
             candidate_strs = f'\nDid you mean one of these: {candidate_strs!r}?'
         return candidate_strs
@@ -286,7 +286,7 @@ def _get_all_supported_regions_str() -> str:
     filter_df = df
     if region is not None:
         filter_df = _filter_region_zone(filter_df, region, zone=None)
-        if len(filter_df) == 0:
+        if not filter_df:
             with ux_utils.print_exception_no_traceback():
                 error_msg = (f'Invalid region {region!r}')
                 candidate_strs = _get_candidate_str(
@@ -310,7 +310,7 @@ def _get_all_supported_regions_str() -> str:
     if zone is not None:
         maybe_region_df = filter_df
         filter_df = filter_df[filter_df['AvailabilityZone'] == zone]
-        if len(filter_df) == 0:
+        if not filter_df:
             region_str = f' for region {region!r}' if region else ''
             df = maybe_region_df if region else df
             with ux_utils.print_exception_no_traceback():
@@ -378,7 +378,7 @@ def get_vcpus_mem_from_instance_type_impl(
     instance_type: str,
 ) -> Tuple[Optional[float], Optional[float]]:
     df = _get_instance_type(df, instance_type, None)
-    if len(df) == 0:
+    if not df:
         with ux_utils.print_exception_no_traceback():
             raise ValueError(f'No instance type {instance_type} found.')
     assert len(set(df['vCPUs'])) == 1, ('Cannot determine the number of vCPUs '
@@ -484,7 +484,7 @@ def get_accelerators_from_instance_type_impl(
     instance_type: str,
 ) -> Optional[Dict[str, Union[int, float]]]:
     df = _get_instance_type(df, instance_type, None)
-    if len(df) == 0:
+    if not df:
         with ux_utils.print_exception_no_traceback():
             raise ValueError(f'No instance type {instance_type} found.')
     row = df.iloc[0]
@@ -518,7 +518,7 @@ def get_instance_type_for_accelerator_impl(
     result = df[(df['AcceleratorName'].str.fullmatch(acc_name, case=False)) &
                 (abs(df['AcceleratorCount'] - acc_count) <= 0.01)]
     result = _filter_region_zone(result, region, zone)
-    if len(result) == 0:
+    if not result:
         fuzzy_result = df[
             (df['AcceleratorName'].str.contains(acc_name, case=False)) &
             (df['AcceleratorCount'] >= acc_count)]
@@ -527,7 +527,7 @@ def get_instance_type_for_accelerator_impl(
         fuzzy_result = fuzzy_result[['AcceleratorName',
                                      'AcceleratorCount']].drop_duplicates()
         fuzzy_candidate_list = []
-        if len(fuzzy_result) > 0:
+        if fuzzy_result:
             for _, row in fuzzy_result.iterrows():
                 acc_cnt = float(row['AcceleratorCount'])
                 acc_count_display = (int(acc_cnt) if acc_cnt.is_integer() else
@@ -539,7 +539,7 @@ def get_instance_type_for_accelerator_impl(
     result = _filter_with_cpus(result, cpus)
     result = _filter_with_mem(result, memory)
     result = _filter_region_zone(result, region, zone)
-    if len(result) == 0:
+    if not result:
         return ([], [])
 
     # Current strategy: choose the cheapest instance
@@ -680,7 +680,7 @@ def get_image_id_from_tag_impl(df: 'pd.DataFrame', tag: str,
     df = _filter_region_zone(df, region, zone=None)
     assert len(df) <= 1, ('Multiple images found for tag '
                           f'{tag} in region {region}')
-    if len(df) == 0:
+    if not df:
         return None
     image_id = df['ImageId'].iloc[0]
     if pd.isna(image_id):
@@ -694,4 +694,4 @@ def is_image_tag_valid_impl(df: 'pd.DataFrame', tag: str,
     df = df[df['Tag'] == tag]
     df = _filter_region_zone(df, region, zone=None)
     df = df.dropna(subset=['ImageId'])
-    return len(df) > 0
+    return bool(df)

sky/clouds/service_catalog/data_fetchers/fetch_azure.py

@@ -134,7 +134,7 @@ def get_pricing_df(region: Optional[str] = None) -> 'pd.DataFrame':
         content_str = r.content.decode('ascii')
         content = json.loads(content_str)
         items = content.get('Items', [])
-        if len(items) == 0:
+        if not items:
             break
         all_items += items
         url = content.get('NextPageLink')

sky/clouds/service_catalog/data_fetchers/fetch_vsphere.py

@@ -534,7 +534,7 @@ def initialize_images_csv(csv_saving_path: str, vc_object,
                         gpu_name = tag_name.split('-')[1]
                         if gpu_name not in gpu_tags:
                             gpu_tags.append(gpu_name)
-                if len(gpu_tags) > 0:
+                if gpu_tags:
                     gpu_tags_str = str(gpu_tags).replace('\'', '\"')
                     f.write(f'{item.id},{vcenter_name},{item_cpu},{item_memory}'
                             f',,,\'{gpu_tags_str}\'\n')

sky/clouds/utils/scp_utils.py

@@ -65,7 +65,7 @@ def __setitem__(self, instance_id: str, value: Optional[Dict[str,
         if value is None:
             if instance_id in metadata:
                 metadata.pop(instance_id)  # del entry
-            if len(metadata) == 0:
+            if not metadata:
                 if os.path.exists(self.path):
                     os.remove(self.path)
                 return
@@ -84,7 +84,7 @@ def refresh(self, instance_ids: List[str]) -> None:
         for instance_id in list(metadata.keys()):
             if instance_id not in instance_ids:
                 del metadata[instance_id]
-        if len(metadata) == 0:
+        if not metadata:
             os.remove(self.path)
             return
         with open(self.path, 'w', encoding='utf-8') as f:
@@ -410,7 +410,7 @@ def list_security_groups(self, vpc_id=None, sg_name=None):
             parameter.append('vpcId=' + vpc_id)
         if sg_name is not None:
             parameter.append('securityGroupName=' + sg_name)
-        if len(parameter) > 0:
+        if parameter:
             url = url + '?' + '&'.join(parameter)
         return self._get(url)