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// 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.
///! This example demonstrates dealing with mixed types dynamically at runtime
use std::sync::Arc;
extern crate arrow;
use arrow::array::*;
use arrow::datatypes::*;
use arrow::error::Result;
use arrow::record_batch::*;
fn main() -> Result<()> {
// define schema
let schema = Schema::new(vec![
Field::new("id", DataType::Int32, false),
Field::new(
"nested",
DataType::Struct(vec![
Field::new("a", DataType::Utf8, false),
Field::new("b", DataType::Float64, false),
Field::new("c", DataType::Float64, false),
]),
false,
),
]);
// create some data
let id = Int32Array::from(vec![1, 2, 3, 4, 5]);
let nested = StructArray::from(vec![
(
Field::new("a", DataType::Utf8, false),
Arc::new(BinaryArray::from(vec!["a", "b", "c", "d", "e"])) as Arc<dyn Array>,
),
(
Field::new("b", DataType::Float64, false),
Arc::new(Float64Array::from(vec![1.1, 2.2, 3.3, 4.4, 5.5])),
),
(
Field::new("c", DataType::Float64, false),
Arc::new(Float64Array::from(vec![2.2, 3.3, 4.4, 5.5, 6.6])),
),
]);
// build a record batch
let batch =
RecordBatch::try_new(Arc::new(schema), vec![Arc::new(id), Arc::new(nested)])?;
Ok(process(&batch))
}
/// Create a new batch by performing a projection of id, nested.c
fn process(batch: &RecordBatch) {
let id = batch.column(0);
let nested = batch
.column(1)
.as_any()
.downcast_ref::<StructArray>()
.unwrap();
let _nested_b = nested
.column(1)
.as_any()
.downcast_ref::<Float64Array>()
.unwrap();
let nested_c: &Float64Array = nested
.column(2)
.as_any()
.downcast_ref::<Float64Array>()
.unwrap();
let projected_schema = Schema::new(vec![
Field::new("id", DataType::Int32, false),
Field::new("sum", DataType::Float64, false),
]);
let _ = RecordBatch::try_new(
Arc::new(projected_schema),
vec![
id.clone(), // NOTE: this is cloning the Arc not the array data
Arc::new(Float64Array::from(nested_c.data())),
],
);
}
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