Add sharding script

README.md

@@ -67,4 +67,66 @@ with open(f"subset_{args.tokens}.json", "w") as outfile:
     json.dump(split, outfile)
 ```
 
-Feel free to modify and use this script to create subsets of other datasets.
+Feel free to modify and use this script to create subsets of other datasets.
+
+The dataset was sharded using the following script:
+
+```python
+import json
+import gzip
+import math
+from pathlib import Path
+
+def shard_dataset(input_file, output_dir, num_shards=4):
+    """
+    Shard a JSON dataset into multiple gzipped JSON lines files.
+    
+    Args:
+        input_file (str): Path to the input JSON file
+        output_dir (str): Directory where shards will be saved
+        num_shards (int): Number of shards to create
+    """
+    # Create output directory if it doesn't exist
+    Path(output_dir).mkdir(parents=True, exist_ok=True)
+    
+    # Load the dataset
+    print(f"Loading dataset from {input_file}...")
+    with open(input_file, 'r') as f:
+        data = json.load(f)
+    
+    # Extract the training examples
+    train_examples = data["train"]
+    total_examples = len(train_examples)
+    examples_per_shard = math.ceil(total_examples / num_shards)
+    
+    print(f"Found {total_examples} examples, splitting into {num_shards} shards")
+    
+    # Create each shard
+    for shard_idx in range(num_shards):
+        # Calculate start and end indices for this shard
+        start_idx = shard_idx * examples_per_shard
+        end_idx = min((shard_idx + 1) * examples_per_shard, total_examples)
+        
+        # Format the filename with zero-padding
+        filename = f"train-{shard_idx:05d}-of-{num_shards:05d}.jsonl.gz"
+        filepath = Path(output_dir) / filename
+        
+        print(f"Creating shard {shard_idx+1}/{num_shards}: {filename}")
+        
+        # Write the shard as gzipped JSON lines
+        with gzip.open(filepath, 'wt', encoding='utf-8') as f:
+            for i in range(start_idx, end_idx):
+                # Write each example as a JSON line
+                json_line = json.dumps(train_examples[i])
+                f.write(json_line + '\n')
+    
+    print(f"Finished creating {num_shards} shards in {output_dir}")
+
+if __name__ == "__main__":
+    # Configuration - update these paths as needed
+    input_json_file = "1B_sample/train.json"  # Update this path
+    output_directory = "1B_sample/sharded_dataset"           # Update this if needed
+    
+    # Shard the dataset into 4 parts
+    shard_dataset(input_json_file, output_directory, num_shards=4)
+```