[GitHub] [arrow] pitrou commented on a change in pull request #7272: ARROW-8314: [Python] Add a Table.select method to select a subset of columns

[GitBox <gi...@apache.org>]

pitrou commented on a change in pull request #7272:
URL: https://github.com/apache/arrow/pull/7272#discussion_r443596563



##########
File path: cpp/src/arrow/table.cc
##########
@@ -362,6 +362,23 @@ Result<std::shared_ptr<Table>> Table::RenameColumns(
   return Table::Make(::arrow::schema(std::move(fields)), std::move(columns), num_rows());
 }
 
+Result<std::shared_ptr<Table>> Table::SelectColumns(
+    const std::vector<int>& indices) const {
+  int n = indices.size();
+
+  std::vector<std::shared_ptr<ChunkedArray>> columns(n);
+  std::vector<std::shared_ptr<Field>> fields(n);
+  for (int i = 0; i < n; i++) {
+    int pos = indices[i];
+    columns[i] = column(pos);
+    fields[i] = field(pos);
+  }
+
+  auto new_schema =
+      std::make_shared<arrow::Schema>(std::move(fields), schema()->metadata());

Review comment:
       Yes, metadata is supposed to be immutable, so no point in copying it.




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