migrating-0.5.0.rst

To petastorm 0.5.0

Petastorm 0.5.0 has some breaking changes from previous versions. These include:

• Users should use :func:`~petastorm.reader.make_reader`, instead of instantiating :class:`~petastorm.reader.Reader` directly to create a new instances
• It is still possible (although discouraged in most cases) to instantitate :class:`~petastorm.reader.Reader`. Some of its argument has changed.

Use :func:`~petastorm.reader.make_reader` to instantiate a reader instance

Use :func:`~petastorm.reader.make_reader` to create a new instance of a reader. :func:`~petastorm.reader.make_reader` takes arguments that are almost similar to constructor arguments of :class:`~petastorm.reader.Reader`. The following list enumerates the differences:

• reader_pool_type: takes one of the strings: 'thread', 'process', 'dummy' (instead of ThreadPool(), ProcessPool() and DummyPool() object instances). Pass number of workers using workers_count argument.
• training_partition and num_training_partitions were renamed into cur_shard and shard_count.
• shuffle and shuffle_options were replaced by shuffle_row_groups=True, shuffle_row_drop_partitions=1

from petastorm.reader import Reader
reader = Reader(dataset_url,
                reader_pool=ThreadPool(5),
                training_partition=1, num_training_partitions=5,
                shuffle_options=ShuffleOptions(shuffle_row_groups=False))

To:

from petastorm import make_reader
reader = make_reader(dataset_url,
                     reader_pool_type='thread',
                     workers_count=5,
                     cur_shard=1, shard_count=5,
                     shuffle_row_groups=False)