feat: Add copy method for tables (#405)

Closes #275 

### Summary of Changes
Added copy method for Table, TaggedTable, Row, Column and looked through
code to change usage to this method.

Co-authored-by: philipgutberlet
<[email protected]>

---------

Co-authored-by: PhilipGutberlet <[email protected]>
Co-authored-by: megalinter-bot <[email protected]>
Co-authored-by: Alexander <[email protected]>

src/safeds/data/tabular/containers/_column.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import copy
 import io
 from collections.abc import Sequence
 from numbers import Number
@@ -1031,3 +1032,19 @@ def _count_missing_values(self) -> int:
         2
         """
         return self._data.isna().sum()
+
+    # ------------------------------------------------------------------------------------------------------------------
+    # Helpers
+    # ------------------------------------------------------------------------------------------------------------------
+
+    def _copy(self) -> Column:
+        """
+        Return a copy of this column.
+
+        Returns
+        -------
+        column : Column
+            The copy of this column.
+
+        """
+        return copy.deepcopy(self)

src/safeds/data/tabular/containers/_row.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import copy
 from collections.abc import Mapping
 from typing import TYPE_CHECKING, Any
 
@@ -263,7 +264,7 @@ def __repr__(self) -> str:
         >>> repr(row)
         "Row({'a': 1})"
         """
-        return f"Row({str(self)})"
+        return f"Row({self!s})"
 
     def __str__(self) -> str:
         """
@@ -493,3 +494,18 @@ def _repr_html_(self) -> str:
             The generated HTML.
         """
         return self._data.to_html(max_rows=1, max_cols=self._data.shape[1], notebook=True)
+
+    # ------------------------------------------------------------------------------------------------------------------
+    # Helpers
+    # ------------------------------------------------------------------------------------------------------------------
+
+    def _copy(self) -> Row:
+        """
+        Return a copy of this row.
+
+        Returns
+        -------
+        copy : Row
+            The copy of this row.
+        """
+        return copy.deepcopy(self)

src/safeds/data/tabular/containers/_table.py

@@ -917,7 +917,7 @@ def add_row(self, row: Row) -> Table:
         1  3  4
         """
         int_columns = []
-        result = self.remove_columns([])  # clone
+        result = self._copy()
         if result.number_of_rows == 0:
             int_columns = list(filter(lambda name: isinstance(row[name], int | np.int64), row.column_names))
             if result.number_of_columns == 0:
@@ -974,7 +974,7 @@ def add_rows(self, rows: list[Row] | Table) -> Table:
         if isinstance(rows, Table):
             rows = rows.to_rows()
         int_columns = []
-        result = self.remove_columns([])  # clone
+        result = self._copy()
         for row in rows:
             if result.number_of_rows == 0:
                 int_columns = list(filter(lambda name: isinstance(row[name], int | np.int64), row.column_names))
@@ -1094,7 +1094,7 @@ def keep_only_columns(self, column_names: list[str]) -> Table:
         if len(invalid_columns) != 0:
             raise UnknownColumnNameError(invalid_columns)
 
-        clone = copy.deepcopy(self)
+        clone = self._copy()
         clone = clone.remove_columns(list(set(self.column_names) - set(column_names)))
         return clone
 
@@ -2223,3 +2223,18 @@ def __dataframe__(self, nan_as_null: bool = False, allow_copy: bool = True):  #
         data_copy = self._data.copy()
         data_copy.columns = self.column_names
         return data_copy.__dataframe__(nan_as_null, allow_copy)
+
+    # ------------------------------------------------------------------------------------------------------------------
+    # Helpers
+    # ------------------------------------------------------------------------------------------------------------------
+
+    def _copy(self) -> Table:
+        """
+        Return a copy of this table.
+
+        Returns
+        -------
+        table : Table
+            The copy of this table.
+        """
+        return copy.deepcopy(self)

src/safeds/data/tabular/containers/_tagged_table.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import copy
 from typing import TYPE_CHECKING
 
 from safeds.data.tabular.containers import Column, Table
@@ -169,3 +170,18 @@ def features(self) -> Table:
     @property
     def target(self) -> Column:
         return self._target
+
+    # ------------------------------------------------------------------------------------------------------------------
+    # Helpers
+    # ------------------------------------------------------------------------------------------------------------------
+
+    def _copy(self) -> TaggedTable:
+        """
+        Return a copy of this tagged table.
+
+        Returns
+        -------
+        table : TaggedTable
+            The copy of this tagged table.
+        """
+        return copy.deepcopy(self)

tests/safeds/data/tabular/containers/_column/test_copy.py

@@ -0,0 +1,13 @@
+import pytest
+from safeds.data.tabular.containers import Column
+
+
+@pytest.mark.parametrize(
+    "column",
+    [Column("a"), Column("a", ["a", 3, 0.1])],
+    ids=["empty", "normal"],
+)
+def test_should_copy_table(column: Column) -> None:
+    copied = column._copy()
+    assert copied == column
+    assert copied is not column

tests/safeds/data/tabular/containers/_table/test_copy.py

@@ -0,0 +1,13 @@
+import pytest
+from safeds.data.tabular.containers import Table
+
+
+@pytest.mark.parametrize(
+    "table",
+    [Table(), Table({"a": [], "b": []}), Table({"a": ["a", 3, 0.1], "b": [True, False, None]})],
+    ids=["empty", "empty-rows", "normal"],
+)
+def test_should_copy_table(table: Table) -> None:
+    copied = table._copy()
+    assert copied == table
+    assert copied is not table

tests/safeds/data/tabular/containers/test_row.py

@@ -511,3 +511,15 @@ def test_should_contain_th_element_for_each_column_name(self, row: Row) -> None:
     def test_should_contain_td_element_for_each_value(self, row: Row) -> None:
         for value in row.values():
             assert f"<td>{value}</td>" in row._repr_html_()
+
+
+class TestCopy:
+    @pytest.mark.parametrize(
+        "row",
+        [Row(), Row({"a": [3, 0.1]})],
+        ids=["empty", "normal"],
+    )
+    def test_should_copy_table(self, row: Row) -> None:
+        copied = row._copy()
+        assert copied == row
+        assert copied is not row

tests/safeds/data/tabular/containers/test_tagged_table.py

@@ -85,3 +85,18 @@ def test_should_return_features(self, tagged_table: TaggedTable) -> None:
 class TestTarget:
     def test_should_return_target(self, tagged_table: TaggedTable) -> None:
         assert tagged_table.target == Column("T", [0, 1])
+
+
+class TestCopy:
+    @pytest.mark.parametrize(
+        "tagged_table",
+        [
+            TaggedTable({"a": [], "b": []}, target_name="b", feature_names=["a"]),
+            TaggedTable({"a": ["a", 3, 0.1], "b": [True, False, None]}, target_name="b", feature_names=["a"]),
+        ],
+        ids=["empty-rows", "normal"],
+    )
+    def test_should_copy_tagged_table(self, tagged_table: TaggedTable) -> None:
+        copied = tagged_table._copy()
+        assert copied == tagged_table
+        assert copied is not tagged_table