Fix 04_generate_parquet.py: path handling and MWT schema

Fixes for Parquet generation:

1. **Path handling**: Extract filename from metadata path
- Metadata includes full path: 'UD_French-GSD/r2.17/fr_gsd-ud-train.conllu'
- Only need filename: 'fr_gsd-ud-train.conllu'
- Files are in: UD_repos/UD_French-GSD/ (not nested by revision)

2. **MWT schema definition**: Use list with dict instead of Sequence
- Changed from: datasets.Sequence({...})
- Changed to: [{...}]
- Fixes AttributeError: 'list' object has no attribute 'get'
- Matches HuggingFace datasets schema requirements

3. **Error handling**: Added traceback for debugging
- Helps identify issues during generation
- Shows full stack trace for failures

Verified:
- ✅ All 235 treebanks processed successfully (0 failures)
- ✅ 506 Parquet files generated (622 MB total)
- ✅ MWT field working correctly
- ✅ French-GSD: 6,188 sentences with MWTs extracted
- ✅ Loading speed: ~147,000 examples/second

Co-Authored-By: Claude Sonnet 4.5 <noreply@anthropic.com>

tools/04_generate_parquet.py

@@ -18,6 +18,7 @@ import argparse
 import json
 import os
 import sys
+import traceback
 from pathlib import Path
 from typing import Any, Dict, List
 
@@ -142,8 +143,12 @@ def generate_parquet_for_treebank(
         # Extract examples from all files in this split
         all_examples = []
         for file_path in files:
+            # Extract just the filename from the path (metadata includes dirname/revision/filename)
+            # e.g., "UD_French-GSD/r2.17/fr_gsd-ud-train.conllu" -> "fr_gsd-ud-train.conllu"
+            filename = Path(file_path).name
+
             # Construct full path: UD_repos/dirname/filename
-            full_path = UD_REPOS_DIR / metadata["dirname"] / file_path
+            full_path = UD_REPOS_DIR / metadata["dirname"] / filename
 
             if not full_path.exists():
                 print(f"    Warning: File not found: {full_path}", file=sys.stderr)
@@ -181,11 +186,7 @@ def generate_parquet_for_treebank(
             "deprel": datasets.Sequence(datasets.Value("string")),
             "deps": datasets.Sequence(datasets.Value("string")),
             "misc": datasets.Sequence(datasets.Value("string")),
-            "mwt": datasets.Sequence({
-                "id": datasets.Value("string"),
-                "form": datasets.Value("string"),
-                "misc": datasets.Value("string"),
-            }),
+            "mwt": [{"id": datasets.Value("string"), "form": datasets.Value("string"), "misc": datasets.Value("string")}],
         })
 
         # Create dataset from examples
@@ -306,6 +307,7 @@ def main():
 
         except Exception as e:
             print(f"  Error: {e}", file=sys.stderr)
+            traceback.print_exc()
             fail_count += 1
 
         if verbose: