feat(csvclean): add --remove-empty-columns option

CHANGELOG.rst

@@ -1,3 +1,8 @@
+Unreleased
+----------
+
+-  feat: :doc:`/scripts/csvclean` adds a :code:`--remove-empty-columns` option to drop columns that are empty in all data rows from standard output.
+
 2.2.0 - December 15, 2025
 -------------------------
 

csvkit/cleanup.py

@@ -49,6 +49,7 @@ def __init__(
         # Other
         zero_based=False,
         omit_error_rows=False,
+        report_empty_columns=True,
     ):
         self.reader = reader
         # Checks
@@ -62,6 +63,7 @@ def __init__(
         # Other
         self.zero_based = zero_based
         self.omit_error_rows = omit_error_rows
+        self.report_empty_columns = report_empty_columns
 
         try:
             self.column_names = next(reader)
@@ -71,6 +73,7 @@ def __init__(
             self.column_names = []
 
         self.errors = []
+        self.empty_column_indices = []
 
     def checked_rows(self):
         """
@@ -147,12 +150,14 @@ def checked_rows(self):
 
         if row_count:  # Don't report all columns as empty if there are no data rows.
             if empty_columns := [i for i, count in enumerate(empty_counts) if count == row_count]:
-                offset = 0 if self.zero_based else 1
-                self.errors.append(
-                    Error(
-                        1,
-                        ["" for _ in range(len_column_names)],
-                        f"Empty columns named {', '.join(repr(self.column_names[i]) for i in empty_columns)}! "
-                        f"Try: csvcut -C {','.join(str(i + offset) for i in empty_columns)}",
+                self.empty_column_indices = empty_columns
+                if self.report_empty_columns:
+                    offset = 0 if self.zero_based else 1
+                    self.errors.append(
+                        Error(
+                            1,
+                            ["" for _ in range(len_column_names)],
+                            f"Empty columns named {', '.join(repr(self.column_names[i]) for i in empty_columns)}! "
+                            f"Try: csvcut -C {','.join(str(i + offset) for i in empty_columns)}",
+                        )
                     )
-                )

csvkit/utilities/csvclean.py

@@ -45,6 +45,9 @@ def add_arguments(self):
         self.argparser.add_argument(
             '--fillvalue', dest='fillvalue',
             help='The value with which to fill short rows. Defaults to none.')
+        self.argparser.add_argument(
+            '--remove-empty-columns', dest='remove_empty_columns', action='store_true',
+            help='Remove columns that are empty in all data rows from standard output.')
 
     def main(self):
         if self.additional_input_expected():
@@ -59,6 +62,7 @@ def main(self):
             and not self.args.header_normalize_space
             and not self.args.join_short_rows
             and not self.args.fill_short_rows
+            and not self.args.remove_empty_columns
         ):
             self.argparser.error('No checks or fixes were enabled. See available options with: csvclean --help')
 
@@ -73,7 +77,7 @@ def main(self):
             reader,
             # Checks
             length_mismatch=default or self.args.length_mismatch,
-            empty_columns=default or self.args.empty_columns,
+            empty_columns=default or self.args.empty_columns or self.args.remove_empty_columns,
             # Fixes
             header_normalize_space=self.args.header_normalize_space,
             join_short_rows=self.args.join_short_rows,
@@ -83,6 +87,7 @@ def main(self):
             # Other
             zero_based=self.args.zero_based,
             omit_error_rows=self.args.omit_error_rows,
+            report_empty_columns=default or self.args.empty_columns,
         )
 
         label = self.args.label
@@ -93,9 +98,16 @@ def main(self):
                 label = self.input_file.name
 
         output_writer = agate.csv.writer(self.output_file, **self.writer_kwargs)
-        output_writer.writerow(checker.column_names)
-        for row in checker.checked_rows():
-            output_writer.writerow(row)
+        if self.args.remove_empty_columns:
+            rows = list(checker.checked_rows())
+            keep = [i for i, name in enumerate(checker.column_names) if i not in checker.empty_column_indices]
+            output_writer.writerow([checker.column_names[i] for i in keep])
+            for row in rows:
+                output_writer.writerow([row[i] if i < len(row) else '' for i in keep])
+        else:
+            output_writer.writerow(checker.column_names)
+            for row in checker.checked_rows():
+                output_writer.writerow(row)
 
         if checker.errors:
             error_writer = agate.csv.writer(self.error_file, **self.writer_kwargs)

docs/scripts/csvclean.rst

@@ -76,6 +76,8 @@ Fixes
       1,Alice,US
       2,Bob,CA
 
+-  If a CSV has columns that are empty in every data row, use :code:`--remove-empty-columns` to drop them from standard output.
+
 .. seealso::
 
    :code:`--header-normalize-space` under :ref:`csvclean-usage`.
@@ -140,6 +142,9 @@ Usage
      --fillvalue FILLVALUE
                            The value with which to fill short rows. Defaults to
                            none.
+     --remove-empty-columns
+                           Remove columns that are empty in all data rows from
+                           standard output.
 
 
 See also: :doc:`../common_arguments`.

tests/test_utilities/test_csvclean.py

@@ -168,6 +168,20 @@ def test_empty_columns_zero(self):
             ['1', "Empty columns named 'b', '', ''! Try: csvcut -C 1,3,4", '', '', '', '', ''],
         ])
 
+    def test_remove_empty_columns(self):
+        self.assertCleaned(['--remove-empty-columns', 'examples/test_empty_columns.csv'], [
+            ['a', 'c'],
+            ['a', ''],
+            ['', 'c'],
+            ['', ''],
+        ])
+
+    def test_remove_empty_columns_no_empty(self):
+        self.assertCleaned(['--remove-empty-columns', 'examples/dummy.csv'], [
+            ['a', 'b', 'c'],
+            ['1', '2', '3'],
+        ])
+
     def test_enable_all_checks(self):
         self.assertCleaned(['-a', 'examples/test_empty_columns.csv'], [
             ['a', 'b', 'c', '', ''],