gemseo / core

discipline_data module

Provide a dict-like class for storing disciplines data.

class gemseo.core.discipline_data.DisciplineData(data, input_to_namespaced=None, output_to_namespaced=None)

Bases: collections.abc.MutableMapping

A dict-like class for handling disciplines data.

This class replaces a standard dictionary that was previously used for storing discipline data. It allows handling values bound to :class:`pandas.DataFrame`s as if they were multiple items bound to :class:`numpy.ndarray`s. Then, an object of this class may be used as if it was a standard dictionary containing :class:`numpy.ndarray`s, which is the assumption made by the clients of the :class:`MDODiscipline`s subclasses.

As compared to a standard dictionary, the methods of this class may hide the values bound to :class:`pandas.DataFrame`s and instead expose the items of those latter as if they belonged to the dictionary.

If a dict-like object is provided when creating a DiscplineData object, its contents is shared with this latter, such that any changes performed via a DiscplineData object is reflected into the passed in dict-like object.

If a DiscplineData is created from another one, their contents are shared.

A separator, by default ~, is used to identify the keys of the items that are bound to an array inside a pandas.DataFrame. Such a key is composed of the key from the shared dict-like object, the separator and the name of the target column of the pandas.DataFrame. When such a key is queried, a numpy.ndarray view of the pandas.DataFrame column is provided.

Printing a DiscplineData object prints the shared dict-like object.

Nested dictionaries are also supported.

Examples

>>> from gemseo.core.discipline_data import DisciplineData
>>> import numpy as np
>>> import pandas as pd
>>> data = {
...         'x': 0,
...         'y': pd.DataFrame(data={'a': np.array([0])}),
...     }
>>> disc_data = DisciplineData(data)
>>> disc_data['x']
0
>>> disc_data['y']
   a
0  0
>>> # DataFrame content can be accessed with the ~ separator.
>>> disc_data['y~a']
array([0])
>>> # New columns can be inserted into a DataFrame with the ~ separator.
>>> disc_data['y~b'] = np.array([1])
>>> data['y']['b']
0    1
Name: b, dtype: int64
>>> # New DataFrame can be added.
>>> disc_data['z~c'] = np.array([2])
>>> data['z']
   c
0  2
>>> type(data['z'])
<class 'pandas.core.frame.DataFrame'>
>>> # DataFrame columns can be deleted.
>>> del disc_data['z~c']
>>> data['z']
Empty DataFrame
Columns: []
Index: [0]
>>> # Iterating is only done over the exposed keys.
>>> list(disc_data)
['x', 'y~a', 'y~b']
>>> # The length is consistent with the iterator.
>>> len(disc_data)
3

Parameters

• data (MutableMapping[str, Any]) – A dict-like object or a DisciplineData object.

• input_to_namespaced (Optional[MutableMapping[str, Union[str, List[str]]]]) –

  The mapping from input data names to their prefixed names.

  By default it is set to None.

• output_to_namespaced (Optional[MutableMapping[str, Union[str, List[str]]]]) –

  The mapping from output data names to their prefixed names.

  By default it is set to None.

Return type

None

clear() → None.  Remove all items from D.

copy()

Create a shallow copy.

Returns

The shallow copy.

Return type

gemseo.core.discipline_data.DisciplineData

get(k[, d]) → D[k] if k in D, else d.  d defaults to None.

items() → a set-like object providing a view on D's items

keys() → a set-like object providing a view on D's keys

pop(k[, d]) → v, remove specified key and return the corresponding value.

If key is not found, d is returned if given, otherwise KeyError is raised.

popitem() → (k, v), remove and return some (key, value) pair

as a 2-tuple; but raise KeyError if D is empty.

setdefault(k[, d]) → D.get(k,d), also set D[k]=d if k not in D

update([E, ]**F) → None.  Update D from mapping/iterable E and F.

If E present and has a .keys() method, does: for k in E: D[k] = E[k] If E present and lacks .keys() method, does: for (k, v) in E: D[k] = v In either case, this is followed by: for k, v in F.items(): D[k] = v

values() → an object providing a view on D's values

SEPARATOR = '~'

The character used to separate the shared dict key from the column of a pandas DataFrame.