added csv_to_parquet function

pyproject.toml

@@ -11,7 +11,8 @@ dependencies = [
  "dimcli",
  "polars>=1.2",
  "pyalex",
- "more-itertools"
+ "more-itertools",
+ "pyarrow"
 ]
 
 [tool.pytest.ini_options]

rialto_airflow/utils.py

@@ -1,7 +1,12 @@
 import csv
 import datetime
-from pathlib import Path
 import re
+import sys
+from itertools import batched
+from pathlib import Path
+
+import pyarrow
+from pyarrow.parquet import ParquetWriter
 
 
 def create_snapshot_dir(data_dir):
@@ -63,3 +68,18 @@ def normalize_doi(doi):
  doi = re.sub("^doi: ", "", doi)
 
  return doi
+
+
+def csv_to_parquet(csv_file, parquet_file, batch_size=10_000):
+ csv.field_size_limit(sys.maxsize)
+
+ csv_input = open(csv_file)
+ reader = csv.DictReader(csv_input)
+
+ # naively assume all columns are strings
+ schema = pyarrow.schema([(name, pyarrow.string()) for name in reader.fieldnames])
+
+ with ParquetWriter(open(parquet_file, "wb"), schema, compression="zstd") as writer:
+ for rows in batched(reader, batch_size):
+ table = pyarrow.Table.from_pylist(rows, schema)
+ writer.write_table(table)

test/test_utils.py

@@ -2,6 +2,7 @@
 from pathlib import Path
 
 import pytest
+import polars
 
 from rialto_airflow import utils
 
@@ -67,3 +68,14 @@ def test_normalize_doi():
  == "10.1103/physrevlett.96.07390"
  )
  assert utils.normalize_doi(" doi: 10.1234/5678 ") == "10.1234/5678"
+
+
+def test_csv_to_parquet(tmp_path):
+ csv_file = Path("test/data/authors.csv")
+ parquet_file = tmp_path / "authors.parquet"
+ utils.csv_to_parquet(csv_file, parquet_file)
+
+ assert parquet_file.is_file()
+ df = polars.read_parquet(parquet_file)
+
+ assert df.shape == (10, 2)