Add example of dataframe API aggregations

datafusion-examples/examples/csv_compressed.rs

@@ -0,0 +1,56 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use datafusion::datasource::file_format::file_compression_type::FileCompressionType;
+use datafusion::error::Result;
+use datafusion::prelude::*;
+
+/// This example demonstrates executing a simple query against a compressed CSV file
+#[tokio::main]
+async fn main() -> Result<()> {
+ // create local execution context
+ let ctx = SessionContext::new();
+
+ let testdata = datafusion::test_util::arrow_test_data();
+
+ // register csv file with the execution context
+ ctx.register_csv(
+ "aggregate_test_100",
+ &format!("{testdata}/csv/aggregate_test_100.csv"),
+ CsvReadOptions::new(),
+ )
+ .await?;
+
+ // query compressed CSV with specific options
+ let csv_options = CsvReadOptions::default()
+ .has_header(true)
+ .file_compression_type(FileCompressionType::GZIP)
+ .file_extension("csv.gz");
+ let df = ctx
+ .read_csv(
+ &format!("{testdata}/csv/aggregate_test_100.csv.gz"),
+ csv_options,
+ )
+ .await?;
+ let df = df
+ .filter(col("c1").eq(lit("a")))?
+ .select_columns(&["c2", "c3"])?;
+
+ df.show().await?;
+
+ Ok(())
+}

datafusion-examples/examples/csv_dataframe.rs

@@ -0,0 +1,48 @@
+// Licensed to the Apache Software Foundation (ASF) under one
+// or more contributor license agreements. See the NOTICE file
+// distributed with this work for additional information
+// regarding copyright ownership. The ASF licenses this file
+// to you under the Apache License, Version 2.0 (the
+// "License"); you may not use this file except in compliance
+// with the License. You may obtain a copy of the License at
+//
+// http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing,
+// software distributed under the License is distributed on an
+// "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+// KIND, either express or implied. See the License for the
+// specific language governing permissions and limitations
+// under the License.
+
+use datafusion::error::Result;
+use datafusion::functions_aggregate::count::count;
+use datafusion::prelude::*;
+
+/// This example demonstrates executing a DataFrame operation against an Arrow data source (CSV) and
+/// fetching results. See `csv_sql.rs` for a SQL version of this example.
+#[tokio::main]
+async fn main() -> Result<()> {
+ // create local execution context
+ let ctx = SessionContext::new();
+
+ let testdata = datafusion::test_util::arrow_test_data();
+
+ // execute the query
+ let df = ctx
+ .read_csv(
+ &format!("{testdata}/csv/aggregate_test_100.csv"),
+ CsvReadOptions::new(),
+ )
+ .await?
+ .filter(col("c11").gt(lit(0.1)).and(col("c11").lt(lit(0.9))))?
+ .aggregate(
+ vec![col("c1")],
+ vec![min(col("c12")), max(col("c12")), count(wildcard())],
+ )?;
+
+ // print the results
+ df.show().await?;
+
+ Ok(())
+}

datafusion-examples/examples/csv_sql.rs

@@ -15,12 +15,11 @@
 // specific language governing permissions and limitations
 // under the License.
 
-use datafusion::datasource::file_format::file_compression_type::FileCompressionType;
 use datafusion::error::Result;
 use datafusion::prelude::*;
 
 /// This example demonstrates executing a simple query against an Arrow data source (CSV) and
-/// fetching results
+/// fetching results. See `csv_dataframe.rs` for a DataFrame version of this example.
 #[tokio::main]
 async fn main() -> Result<()> {
  // create local execution context
@@ -39,7 +38,7 @@ async fn main() -> Result<()> {
  // execute the query
  let df = ctx
  .sql(
- "SELECT c1, MIN(c12), MAX(c12) \
+ "SELECT c1, MIN(c12), MAX(c12), COUNT(*) \
  FROM aggregate_test_100 \
  WHERE c11 > 0.1 AND c11 < 0.9 \
  GROUP BY c1",
@@ -49,22 +48,5 @@ async fn main() -> Result<()> {
  // print the results
  df.show().await?;
 
- // query compressed CSV with specific options
- let csv_options = CsvReadOptions::default()
- .has_header(true)
- .file_compression_type(FileCompressionType::GZIP)
- .file_extension("csv.gz");
- let df = ctx
- .read_csv(
- &format!("{testdata}/csv/aggregate_test_100.csv.gz"),
- csv_options,
- )
- .await?;
- let df = df
- .filter(col("c1").eq(lit("a")))?
- .select_columns(&["c2", "c3"])?;
-
- df.show().await?;
-
  Ok(())
 }