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Dictionary Interface to DataSets

Small python library for managing different sources in a dataset and interfacing with them as dictionaries.

Manages mapping, combining and saving/loading to file.

Using Datasets

Datasets are designed to implement much of the standard python dict class's interface. Additionally, they are designed to be used in with context blocks.

d0 = Dataset.from_dict({'x': 1, 'y': 3})
d1 = Dataset.from_function(lambda x: x*3)

zipped = Dataset.zip(d0, d1)
with zipped:
    print(zipped['x'])           # (1, 'xxx')
    print(zipped['y'])           # (3, 'yyy')
    print('x' in zipped)         # True
    print('z' in zipped)         # False
    print(tuple(zipped.keys()))  # ('x', 'y'), or possibly ('y', 'x')
    try:
        print(zipped['z'])       # KeyError
    except KeyError:
        print('"z" not in zipped')

While not all datasets require use inside with blocks, it is highly recommended client code use them in such a way such that implementations can later be changed to require this. For example, WrappedDictDatasets do not require opening/closing. The source of the dataset may later be changed to a JsonDataset, which does. Code that runs without a with block will work for a WrappedDictDataset, but not a JsonDataset.

Saving/loading

A number of implementations exist for writing/loading from file and are included in file_io. Currently these include:

• json
• numpy
• hdf5

Implementing your own Dataset

Most datasets can be formed by a combination of mapping, key mapping and combining simpler datasets, or wrapping base dictionaries. If you do need to implement your own - e.g. for loading from a custom data format file, UnwritableDataset is the base class to extend if writing is not required. Extensions must implement only __getitem__ and keys at the least.

If writing is required, Dataset can be extended. In addition to the method required for UnwritableDataset, __setitem__ and __delitem__ must be implemented.