[Doc] Change random.py to random_partition.py in guide on distributed partition pipeline (#4438)

* Update distributed-preprocessing.rst

* Update
Co-authored-by: Ubuntu <ubuntu@ip-172-31-9-26.ap-northeast-1.compute.internal>

docs/source/guide/distributed-preprocessing.rst

@@ -291,13 +291,13 @@ Step.1 Graph Partitioning
 This step reads the chunked graph data and calculates which partition each node
 should belong to. The results are saved in a set of *partition assignment files*.
 For example, to randomly partition MAG240M-LSC to two parts, run the
-``partition_algo/random.py`` script in the ``tools`` folder:
+``partition_algo/random_partition.py`` script in the ``tools`` folder:
 
 .. code-block:: bash
 
-    python /my/repo/dgl/tools/partition_algo/random.py
-        --metadata /mydata/MAG240M-LSC_chunked/metadata.json
-        --output_path /mydata/MAG240M-LSC_2parts/
+    python /my/repo/dgl/tools/partition_algo/random_partition.py
+        --in_dir /mydata/MAG240M-LSC_chunked
+        --out_dir /mydata/MAG240M-LSC_2parts
         --num_partitions 2
 
 , which outputs files as follows:

tests/tools/test_dist_part.py

@@ -155,7 +155,7 @@ def test_part_pipeline():
         in_dir = os.path.join(root_dir, 'chunked-data')
         output_dir = os.path.join(root_dir, '2parts')
         os.system('python tools/partition_algo/random_partition.py '\
-                  '--metadata {}/metadata.json --output_path {} --num_partitions {}'.format(
+                  '--in_dir {} --out_dir {} --num_partitions {}'.format(
                     in_dir, output_dir, num_chunks))
         for ntype in ['author', 'institution', 'paper']:
             fname = os.path.join(output_dir, '{}.txt'.format(ntype))

tools/partition_algo/random_partition.py

@@ -35,15 +35,14 @@ def random_partition(metadata, num_parts, output_path):
 if __name__ == '__main__':
     parser = argparse.ArgumentParser()
     parser.add_argument(
-            '--metadata', type=str, help='input metadata file of the chunked graph format')
+            '--in_dir', type=str, help='input directory that contains the metadata file')
     parser.add_argument(
-            '--output_path', type=str, help='output directory')
+            '--out_dir', type=str, help='output directory')
     parser.add_argument(
             '--num_partitions', type=int, help='number of partitions')
     logging.basicConfig(level='INFO')
     args = parser.parse_args()
-    with open(args.metadata) as f:
+    with open(os.path.join(args.in_dir, 'metadata.json')) as f:
         metadata = json.load(f)
-    output_path = args.output_path
     num_parts = args.num_partitions
-    random_partition(metadata, num_parts, output_path)
+    random_partition(metadata, num_parts, args.out_dir)