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https://issues.apache.org/jira/browse/ARROW-1865?page=com.atlassian.jira.plugin.system.issuetabpanels:comment-tabpanel&focusedCommentId=16276105#comment-16276105
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ASF GitHub Bot commented on ARROW-1865:
---------------------------------------
wesm closed pull request #1373: ARROW-1865: [C++] Do not alter number of rows
attribute when removing last column from Table
URL: https://github.com/apache/arrow/pull/1373
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diff --git a/cpp/src/arrow/table-test.cc b/cpp/src/arrow/table-test.cc
index 8a2288710..3f1c6be3a 100644
--- a/cpp/src/arrow/table-test.cc
+++ b/cpp/src/arrow/table-test.cc
@@ -404,6 +404,26 @@ TEST_F(TestTable, RemoveColumn) {
ASSERT_TRUE(result->Equals(*expected));
}
+TEST_F(TestTable, RemoveColumnEmpty) {
+ // ARROW-1865
+ const int64_t length = 10;
+
+ auto f0 = field("f0", int32());
+ auto schema = ::arrow::schema({f0});
+ auto a0 = MakeRandomArray<Int32Array>(length);
+
+ auto table = Table::Make(schema, {std::make_shared<Column>(f0, a0)});
+
+ std::shared_ptr<Table> empty;
+ ASSERT_OK(table->RemoveColumn(0, &empty));
+
+ ASSERT_EQ(table->num_rows(), empty->num_rows());
+
+ std::shared_ptr<Table> added;
+ ASSERT_OK(empty->AddColumn(0, table->column(0), &added));
+ ASSERT_EQ(table->num_rows(), added->num_rows());
+}
+
TEST_F(TestTable, AddColumn) {
const int64_t length = 10;
MakeExample1(length);
diff --git a/cpp/src/arrow/table.cc b/cpp/src/arrow/table.cc
index 129524b7e..2cf6c2652 100644
--- a/cpp/src/arrow/table.cc
+++ b/cpp/src/arrow/table.cc
@@ -202,7 +202,8 @@ class SimpleTable : public Table {
std::shared_ptr<Schema> new_schema;
RETURN_NOT_OK(schema_->RemoveField(i, &new_schema));
- *out = Table::Make(new_schema, internal::DeleteVectorElement(columns_, i));
+ *out = Table::Make(new_schema, internal::DeleteVectorElement(columns_, i),
+ this->num_rows());
return Status::OK();
}
diff --git a/python/pyarrow/tests/test_table.py
b/python/pyarrow/tests/test_table.py
index ab012340c..e72761d32 100644
--- a/python/pyarrow/tests/test_table.py
+++ b/python/pyarrow/tests/test_table.py
@@ -312,6 +312,20 @@ def test_table_remove_column():
assert t2.equals(expected)
+def test_table_remove_column_empty():
+ # ARROW-1865
+ data = [
+ pa.array(range(5)),
+ ]
+ table = pa.Table.from_arrays(data, names=['a'])
+
+ t2 = table.remove_column(0)
+ assert len(t2) == len(table)
+
+ t3 = t2.add_column(0, table[0])
+ assert t3.equals(table)
+
+
def test_concat_tables():
data = [
list(range(5)),
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> [C++] Adding a column to an empty Table fails
> ---------------------------------------------
>
> Key: ARROW-1865
> URL: https://issues.apache.org/jira/browse/ARROW-1865
> Project: Apache Arrow
> Issue Type: Bug
> Components: C++
> Reporter: Uwe L. Korn
> Assignee: Wes McKinney
> Labels: pull-request-available
> Fix For: 0.8.0
>
>
> If we remove a column from a table and add new column (probably a casted
> version of it), it is rejected as the Table {{num_rows}} was reset to 0:
> {code}
> Invalid: Added column's length must match table's length. Expected length 0
> but got length 1
> {code}
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