mindspore.dataset.SubsetSampler

class mindspore.dataset.SubsetSampler(indices, num_samples=None)[source]

Samples the elements from a sequence of indices.

Parameters

  • indices (Iterable) – A sequence of indices (Any iterable Python object but string).

  • num_samples (int, optional) – Number of elements to sample. Default: None, which means sample all elements.

Raises

  • TypeError – If elements of indices are not of type number.

  • TypeError – If num_samples is not of type int.

  • ValueError – If num_samples is a negative value.

Examples

>>> indices = [0, 1, 2, 3, 4, 5]
>>>
>>> # creates a SubsetSampler, will sample from the provided indices
>>> sampler = ds.SubsetSampler(indices)
>>> dataset = ds.ImageFolderDataset(image_folder_dataset_dir,
...                                 num_parallel_workers=8,
...                                 sampler=sampler)
add_child(sampler)

Add a sub-sampler for given sampler. The parent will receive all data from the output of sub-sampler sampler and apply its sample logic to return new samples.

Parameters

sampler (Sampler) – Object used to choose samples from the dataset. Only builtin samplers(DistributedSampler, PKSampler, RandomSampler, SequentialSampler, SubsetRandomSampler, WeightedRandomSampler) are supported.

Examples

>>> sampler = ds.SequentialSampler(start_index=0, num_samples=3)
>>> sampler.add_child(ds.RandomSampler(num_samples=4))
>>> dataset = ds.Cifar10Dataset(cifar10_dataset_dir, sampler=sampler)
get_child()

Get the child sampler of given sampler.

Returns

Sampler, The child sampler of given sampler.

Examples

>>> sampler = ds.SequentialSampler(start_index=0, num_samples=3)
>>> sampler.add_child(ds.RandomSampler(num_samples=2))
>>> child_sampler = sampler.get_child()