Trim comma-padded blank rows in CSV table conversion

packages/markitdown/src/markitdown/converters/_csv_converter.py

@@ -29,10 +29,22 @@ def _escape_table_cell(value: str) -> str:
     return value.replace("\r\n", " ").replace("\n", " ").replace("\r", " ")
 
 
+def _is_blank_row(row: list[str]) -> bool:
+    """Whether a parsed row carries no data.
+
+    Writers that pad every record to the column width emit a blank row as
+    ",," rather than an empty line -- ``pandas.DataFrame.to_csv`` does this
+    for all-NaN rows -- so a run of empty (or whitespace-only) cells is the
+    same blank row. This is the same reading the PDF table builder already
+    uses in ``_pdf_converter._to_markdown_table``.
+    """
+    return all(not cell.strip() for cell in row)
+
+
 def _trim_outer_blank_rows(rows: list[list[str]]) -> None:
     """Remove empty rows from the beginning and end, and immediately after the header. This operation is performed in-place."""
     start = 0
-    while start < len(rows) and not rows[start]:
+    while start < len(rows) and _is_blank_row(rows[start]):
         start += 1
 
     if start == len(rows):
@@ -41,11 +53,11 @@ def _trim_outer_blank_rows(rows: list[list[str]]) -> None:
 
     header_index = start
     start += 1
-    while start < len(rows) and not rows[start]:
+    while start < len(rows) and _is_blank_row(rows[start]):
         start += 1
 
     end = len(rows)
-    while end > start and not rows[end - 1]:
+    while end > start and _is_blank_row(rows[end - 1]):
         end -= 1
 
     # Remove each blank run at once, rather than shifting the list per row.

packages/markitdown/tests/test_csv.py

@@ -144,6 +144,43 @@ def test_csv_all_blank_input_returns_empty_markdown() -> None:
     assert result == ""
 
 
+def test_csv_comma_padded_blank_rows_are_trimmed() -> None:
+    # A writer that pads every record to the column width writes a blank row
+    # as ",," rather than an empty line; pandas' to_csv does this for all-NaN
+    # rows. Such a row is blank just the same: an outer one must not become an
+    # empty header, nor survive as an empty data row.
+    result = _convert_csv(b",,\nname,age\nAlice,30\n,,\n,,\n")
+
+    assert result == "| name | age |\n| --- | --- |\n| Alice | 30 |"
+
+
+def test_csv_whitespace_padded_blank_rows_are_trimmed() -> None:
+    result = _convert_csv(b" , \nname,age\nAlice,30\n , \n")
+
+    assert result == "| name | age |\n| --- | --- |\n| Alice | 30 |"
+
+
+def test_csv_comma_padded_row_between_data_rows_is_kept() -> None:
+    # Only the outer runs are trimmed; an internal blank row keeps its place,
+    # exactly as the existing blank-line test pins for unpadded blank rows.
+    # (The ",," record carries three empty fields, so it is the widest row.)
+    result = _convert_csv(b"name,age\nAlice,30\n,,\nBob,40\n")
+
+    assert (
+        result == "| name | age |  |\n"
+        "| --- | --- | --- |\n"
+        "| Alice | 30 |  |\n"
+        "|  |  |  |\n"
+        "| Bob | 40 |  |"
+    )
+
+
+def test_csv_blank_row_after_header_is_trimmed() -> None:
+    result = _convert_csv(b"name,age\n,,\nAlice,30\n")
+
+    assert result == "| name | age |\n| --- | --- |\n| Alice | 30 |"
+
+
 @pytest.mark.parametrize(
     "data,expected",
     [