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use std::sync::Arc;
use crate::array::*;
use crate::datatypes::*;
use crate::error::{ArrowError, Result};
#[derive(Clone, Debug)]
pub struct RecordBatch {
schema: SchemaRef,
columns: Vec<Arc<Array>>,
}
impl RecordBatch {
pub fn try_new(schema: SchemaRef, columns: Vec<ArrayRef>) -> Result<Self> {
if columns.is_empty() {
return Err(ArrowError::InvalidArgumentError(
"at least one column must be defined to create a record batch"
.to_string(),
));
}
if schema.fields().len() != columns.len() {
return Err(ArrowError::InvalidArgumentError(format!(
"number of columns({}) must match number of fields({}) in schema",
columns.len(),
schema.fields().len(),
)));
}
let len = columns[0].data().len();
for (i, column) in columns.iter().enumerate() {
if column.len() != len {
return Err(ArrowError::InvalidArgumentError(
"all columns in a record batch must have the same length".to_string(),
));
}
if column.data_type() != schema.field(i).data_type() {
return Err(ArrowError::InvalidArgumentError(format!(
"column types must match schema types, expected {:?} but found {:?} at column index {}",
schema.field(i).data_type(),
column.data_type(),
i)));
}
}
Ok(RecordBatch { schema, columns })
}
pub fn schema(&self) -> SchemaRef {
self.schema.clone()
}
pub fn num_columns(&self) -> usize {
self.columns.len()
}
pub fn num_rows(&self) -> usize {
self.columns[0].data().len()
}
pub fn column(&self, index: usize) -> &ArrayRef {
&self.columns[index]
}
pub fn columns(&self) -> &[ArrayRef] {
&self.columns[..]
}
}
impl From<&StructArray> for RecordBatch {
fn from(struct_array: &StructArray) -> Self {
if let DataType::Struct(fields) = struct_array.data_type() {
let schema = Schema::new(fields.clone());
let columns = struct_array.boxed_fields.clone();
RecordBatch {
schema: Arc::new(schema),
columns,
}
} else {
unreachable!("unable to get datatype as struct")
}
}
}
impl Into<StructArray> for RecordBatch {
fn into(self) -> StructArray {
self.schema
.fields
.iter()
.zip(self.columns.iter())
.map(|t| (t.0.clone(), t.1.clone()))
.collect::<Vec<(Field, ArrayRef)>>()
.into()
}
}
pub trait RecordBatchReader {
fn schema(&self) -> SchemaRef;
fn next_batch(&mut self) -> Result<Option<RecordBatch>>;
}
#[cfg(test)]
mod tests {
use super::*;
use crate::buffer::*;
#[test]
fn create_record_batch() {
let schema = Schema::new(vec![
Field::new("a", DataType::Int32, false),
Field::new("b", DataType::Utf8, false),
]);
let v = vec![1, 2, 3, 4, 5];
let array_data = ArrayData::builder(DataType::Int32)
.len(5)
.add_buffer(Buffer::from(v.to_byte_slice()))
.build();
let a = Int32Array::from(array_data);
let v = vec![b'a', b'b', b'c', b'd', b'e'];
let offset_data = vec![0, 1, 2, 3, 4, 5, 6];
let array_data = ArrayData::builder(DataType::Utf8)
.len(5)
.add_buffer(Buffer::from(offset_data.to_byte_slice()))
.add_buffer(Buffer::from(v.to_byte_slice()))
.build();
let b = BinaryArray::from(array_data);
let record_batch =
RecordBatch::try_new(Arc::new(schema), vec![Arc::new(a), Arc::new(b)])
.unwrap();
assert_eq!(5, record_batch.num_rows());
assert_eq!(2, record_batch.num_columns());
assert_eq!(&DataType::Int32, record_batch.schema().field(0).data_type());
assert_eq!(&DataType::Utf8, record_batch.schema().field(1).data_type());
assert_eq!(5, record_batch.column(0).data().len());
assert_eq!(5, record_batch.column(1).data().len());
}
#[test]
fn create_record_batch_schema_mismatch() {
let schema = Schema::new(vec![Field::new("a", DataType::Int32, false)]);
let a = Int64Array::from(vec![1, 2, 3, 4, 5]);
let batch = RecordBatch::try_new(Arc::new(schema), vec![Arc::new(a)]);
assert!(!batch.is_ok());
}
#[test]
fn create_record_batch_record_mismatch() {
let schema = Schema::new(vec![Field::new("a", DataType::Int32, false)]);
let a = Int32Array::from(vec![1, 2, 3, 4, 5]);
let b = Int32Array::from(vec![1, 2, 3, 4, 5]);
let batch =
RecordBatch::try_new(Arc::new(schema), vec![Arc::new(a), Arc::new(b)]);
assert!(!batch.is_ok());
}
#[test]
fn create_record_batch_from_struct_array() {
let boolean_data = ArrayData::builder(DataType::Boolean)
.len(4)
.add_buffer(Buffer::from([12_u8]))
.build();
let int_data = ArrayData::builder(DataType::Int32)
.len(4)
.add_buffer(Buffer::from([42, 28, 19, 31].to_byte_slice()))
.build();
let struct_array = StructArray::from(vec![
(
Field::new("b", DataType::Boolean, false),
Arc::new(BooleanArray::from(vec![false, false, true, true]))
as Arc<Array>,
),
(
Field::new("c", DataType::Int32, false),
Arc::new(Int32Array::from(vec![42, 28, 19, 31])),
),
]);
let batch = RecordBatch::from(&struct_array);
assert_eq!(2, batch.num_columns());
assert_eq!(4, batch.num_rows());
assert_eq!(
struct_array.data_type(),
&DataType::Struct(batch.schema().fields().to_vec())
);
assert_eq!(batch.column(0).data(), boolean_data);
assert_eq!(batch.column(1).data(), int_data);
}
}