pyarrow.RecordBatchReader

class pyarrow.RecordBatchReader

Bases: _Weakrefable

Base class for reading stream of record batches.

Record batch readers function as iterators of record batches that also provide the schema (without the need to get any batches).

Warning

Do not call this class’s constructor directly, use one of the RecordBatchReader.from_* functions instead.

Notes

To import and export using the Arrow C stream interface, use the _import_from_c and _export_from_c methods. However, keep in mind this interface is intended for expert users.

Examples

>>> import pyarrow as pa
>>> schema = pa.schema([('x', pa.int64())])
>>> def iter_record_batches():
...     for i in range(2):
...         yield pa.RecordBatch.from_arrays([pa.array([1, 2, 3])], schema=schema)
>>> reader = pa.RecordBatchReader.from_batches(schema, iter_record_batches())
>>> print(reader.schema)
x: int64
>>> for batch in reader:
...     print(batch)
pyarrow.RecordBatch
x: int64
pyarrow.RecordBatch
x: int64
__init__(*args, **kwargs)

Methods

__init__(*args, **kwargs)

close(self)

Release any resources associated with the reader.

from_batches(Schema schema, batches)

Create RecordBatchReader from an iterable of batches.

read_all(self)

Read all record batches as a pyarrow.Table.

read_next_batch(self)

Read next RecordBatch from the stream.

read_pandas(self, **options)

Read contents of stream to a pandas.DataFrame.

Attributes

schema

Shared schema of the record batches in the stream.

close(self)

Release any resources associated with the reader.

static from_batches(Schema schema, batches)

Create RecordBatchReader from an iterable of batches.

Parameters:
schemaSchema

The shared schema of the record batches

batchesIterable[RecordBatch]

The batches that this reader will return.

Returns:
readerRecordBatchReader
read_all(self)

Read all record batches as a pyarrow.Table.

Returns:
Table
read_next_batch(self)

Read next RecordBatch from the stream.

Returns:
RecordBatch
Raises:
StopIteration:

At end of stream.

read_pandas(self, **options)

Read contents of stream to a pandas.DataFrame.

Read all record batches as a pyarrow.Table then convert it to a pandas.DataFrame using Table.to_pandas.

Parameters:
**options

Arguments to forward to Table.to_pandas().

Returns:
dfpandas.DataFrame
schema

Shared schema of the record batches in the stream.

Returns:
Schema