Characteristics¶

The galactic.characteristics module defines essential classes for representing characteristics:

Characteristic for the superclass of all characteristics
Valued for characteristics defined by a data
Named for named characteristics
Key for characteristics whose calls to an individual will be retrieved by a key access
Item for characteristics whose calls to an individual will be retrieved by a nth access
Slice for characteristics whose calls to an individual will be retrieved by a slice access
Property for characteristics whose calls to an individual will be retrieved by a property access
Transformation for characteristics that hold a transform operation
Composite for characteristics which contain a collection of other Characteristic instances
Conversion for characteristics that execute a transform operation
Sum for characteristics that execute a sum operation
Comparison for characteristics that need a strict boolean flag used in comparison
Set for characteristics that contains a set of values

class galactic.characteristics.Characteristic(*args: Any, cache: Optional[bool] = True, **kwargs: Any)¶

Bases: object

The Characteristic class is the super class of all characteristics. It is designed for subclassing.

A characteristic can be called on an individual. It returns a data of this individual.

clear() → None ¶: Clear the cache.

__call__(individual: Any) → Any¶

Make this characteristic callable. This method should be overridden in sub-classes.

Keyword Arguments: individual – Any python object
Returns: The individual characteristic
Return type: object

class galactic.characteristics.Composite(*args: galactic.characteristics.main.Characteristic, **kwargs: Any)¶

Bases: galactic.characteristics.main.Characteristic

The Composite class is used as a container of embedded Characteristic instances. It is designed for subclassing.

characteristics¶

The tuple of Characteristic instances hold by this instance.

Type: tuple

__init__(*args: galactic.characteristics.main.Characteristic, **kwargs: Any) → None ¶

Initialise a Composite instance.

Parameters

*args (tuple) – A collection of Characteristic instances
**kwargs – Unused but useful for multi-class inheritance.

Raises

TypeError – If a characteristic is not an instance of Characteristic

class galactic.characteristics.Named(*args: galactic.characteristics.main.Characteristic, name: str, **kwargs: Any)¶

Bases: galactic.characteristics.main.Characteristic

The Named class is used to represent named characteristics. Is is designed for subclassing.

name¶

The name hold by the instance. It is used to name Characteristic instances.

Type: str

__init__(*args: galactic.characteristics.main.Characteristic, name: str, **kwargs: Any) → None ¶

Initialise a Named instance.

Parameters

*args – Unused but useful for multi-class inheritance.
**kwargs – Unused but useful for multi-class inheritance.

Keyword Arguments

name – A name (usually a string)

class galactic.characteristics.Valued(*args: galactic.characteristics.main.Characteristic, data: Any = None, **kwargs: Any)¶

Bases: galactic.characteristics.main.Characteristic

The Valued class is used to hold a data.

data¶: The data hold by the instance.

Example

>>> from galactic.characteristics import Valued
>>> a = Valued(data=5)
>>> print(a)
5
>>> a({})
5

__init__(*args: galactic.characteristics.main.Characteristic, data: Any = None, **kwargs: Any) → None ¶

Initialise a Valued instance.

Parameters

*args – Unused but useful for multi-class inheritance.
**kwargs – Unused but useful for multi-class inheritance.

Keyword Arguments

data – Any python object

class galactic.characteristics.Comparison(strict: bool = False, **kwargs: Any)¶

Bases: galactic.characteristics.main.Characteristic

The Comparison class can be inherited to hold strict property. It is designed for subclassing.

strict¶

The strict property hold by this instance. It is a boolean flag used for strict (or not) Comparison.

Type: bool

__init__(strict: bool = False, **kwargs: Any)¶

Initialise a Comparison instance.

Parameters

*args – Unused but useful for multi-class inheritance.
**kwargs – Unused but useful for multi-class inheritance.

Keyword Arguments

strict – Is the comparison strict?

class galactic.characteristics.Set(values: Iterable[collections.abc.Hashable], **kwargs: Any)¶

Bases: galactic.characteristics.main.Characteristic

A Set characteristics can be inherited to hold a set of values property. It is designed for subclassing.

values¶

The values hold by this instance. It is used to hold a collection of values.

Type: OrderedSet

__init__(values: Iterable[collections.abc.Hashable], **kwargs: Any) → None ¶

Initialise a Set instance.

Parameters

*args – Unused but useful for multi-class inheritance.
**kwargs – Unused but useful for multi-class inheritance.

Keyword Arguments

values (Collection) – A collection of values to be compared with

class galactic.characteristics.Transformation(transform: Optional[function] = None, **kwargs: Any)¶

Bases: galactic.characteristics.main.Characteristic

The Transformation class is used to hold a transform operation. It is designed for subclassing.

transform¶

The transform operation hold by the instance. It is used to apply transformation on values.

Type: Callable

__init__(transform: Optional[function] = None, **kwargs: Any)¶

Initialise a Transformation instance.

Parameters

*args – Unused but useful for multi-class inheritance.
**kwargs – Unused but useful for multi-class inheritance.

Keyword Arguments

transform – A transform operation.

class galactic.characteristics.Key(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, **kwargs: Any)¶

Bases: galactic.characteristics.main.Named, galactic.characteristics.main.Composite

The Key class is used to represent key characteristics.

name¶

The name hold by the instance.

Type: str

characteristics¶

The tuple of Characteristic instances hold by this instance.

Type: tuple

Example

>>> from galactic.characteristics import Key
>>> a = Key(name="x")
>>> print(a)
x
>>> a({"x": 5})
5
>>> a({})
>>> a=Key(Key(name="x"), name="y")
>>> print(a)
x[y]
>>> a({"x": {"y": 5}})
5

__init__(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, **kwargs: Any) → None ¶

Initialize a Key instance.

Parameters: characteristic (Characteristic) – The underlying characteristic.

class galactic.characteristics.Property(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, **kwargs: Any)¶

Bases: galactic.characteristics.main.Named, galactic.characteristics.main.Composite

The Property class is used to represent property characteristics.

name¶

The name hold by the instance.

Type: str

characteristics¶

The tuple of Characteristic instances hold by this instance.

Type: tuple

__init__(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, **kwargs: Any)¶

Initialize a Property instance.

Parameters: characteristic (Characteristic) – The underlying characteristic.

class galactic.characteristics.Item(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, nth: int = 0, **kwargs: Any)¶

Bases: galactic.characteristics.main.Composite

The Item class is used to represent item sequences.

nth¶

The numbering of the element in the sequence.

Type: int

characteristics¶

The tuple of Characteristic instances hold by this instance.

Type: tuple

Example

>>> from galactic.characteristics import Item, Key
>>> a = Item(nth=1)
>>> print(a)
[1]
>>> a([1, 2, 3])
2
>>> a([])
>>> a = Item(Key(name="a"), nth=1)
>>> print(a)
a[1]

__init__(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, nth: int = 0, **kwargs: Any) → None ¶

Initialize a Item instance.

Parameters: characteristic (Characteristic) – The underlying characteristic.
Keyword Arguments: nth (int) – The numbering of the element in the sequence.

class galactic.characteristics.Slice(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, start: Optional[int] = None, end: Optional[int] = None, **kwargs: Any)¶

Bases: galactic.characteristics.main.Composite

The Slice class is used to represent item slices.

start¶

The slice start.

Type: int

end¶

The slice end.

Type: int

characteristics¶

The tuple of Characteristic instances hold by this instance.

Type: tuple

Example

>>> from galactic.characteristics import Slice, Key
>>> a = Slice(start=1)
>>> print(a)
[1:]
>>> a([1, 2, 3])
[2, 3]
>>> a(None)
>>> a = Slice(Key(name="a"), start=1)
>>> print(a)
a[1:]

__init__(characteristic: Optional[galactic.characteristics.main.Characteristic] = None, start: Optional[int] = None, end: Optional[int] = None, **kwargs: Any) → None ¶

Initialize a Slice instance.

Parameters

characteristic (Characteristic) – The underlying characteristic.

Keyword Arguments

start (int) – The slice start.
end (int) – The slice end.

class galactic.characteristics.Conversion(characteristic: galactic.characteristics.main.Characteristic, **kwargs: Any)¶

Bases: galactic.characteristics.main.Composite, galactic.characteristics.main.Transformation, galactic.characteristics.main.Valued

The Conversion class is used to convert a characteristic call to a specific type.

characteristics¶

The characteristics (tuple of Characteristic instances) hold by this instance.

Type: tuple

transform¶

The transform operation hold by the instance.

Type: Callable

data¶: The data hold by the instance.

Example

>>> from galactic.characteristics import Conversion, Key
>>> a = Conversion(Key(name="x"), transform=float, data="nan")
>>> print(a)
x
>>> a({"x": "5"})
5.0
>>> a(4)
nan

__init__(characteristic: galactic.characteristics.main.Characteristic, **kwargs: Any) → None ¶

Initialise a Conversion instance.

Parameters

characteristic (Characteristic) – The embedded characteristics

Keyword Arguments

transform (Callable) – A transform operation (inherited from Transformation.__init__()).
data – Any python object (inherited from Valued.__init__()).

class galactic.characteristics.Sum(*args: galactic.characteristics.main.Characteristic, start: Any = 0, **kwargs: Any)¶

Bases: galactic.characteristics.main.Composite, galactic.characteristics.main.Transformation, galactic.characteristics.main.Valued

The Sum class is used to define a sum over other Characteristic instances.

start¶: Initial value for the sum. It is used as a beginning for the sum calculus.

characteristics¶

The characteristics (tuple of Characteristic instances) hold by this instance.

Type: tuple

transform¶

The transform operation hold by the instance.

Type: Callable

data¶: The data hold by the instance.

Example

>>> from galactic.characteristics import Key, Sum
>>> s = Sum(Key(name="x"), Key(name="y"), start=[], data=None)
>>> print(s)
(x+y)
>>> s({})
>>> s({"x": [1]})
>>> s({"x": [1], "y": [2]})
[1, 2]
>>>

Example

>>> from galactic.characteristics import Key, Sum
>>> s = Sum(Key(name="x"), Key(name="y"), start=0, data="nan", transform=float)
>>> print(s)
(x+y)
>>> s({})
nan
>>> s({"x": 1})
nan
>>> s({"x": 1, "y": 2})
3.0
>>>

__init__(*args: galactic.characteristics.main.Characteristic, start: Any = 0, **kwargs: Any)¶

Initialise a Sum instance.

Parameters

*args (tuple) – A collection of Characteristic instances to sum (inherited from Composite.__init__())
**kwargs – Unused but useful for multi-class inheritance.

Keyword Arguments

start – Initial data for the sum
transform (Callable) – A transform operation (inherited from Transformation.__init__()).
data – Any python object (inherited from Valued.__init__()).