"""Defines interfaces related to various operations on table-like data."""
from abc import abstractmethod, ABC
from typing import Union, Iterable
__all__ = ['TabularIterator', 'TabularRetriever', 'TabularMutator']
[docs]class TabularRetriever(ABC):
"""Operations on table-like data.
Classes implementing this interface gain the ability to perform various operations
on data structures that resemble a table (have indexable columns, rows, etc):
most importantly they can slice through the data (retrieve specific row or column)
"""
[docs] @abstractmethod
def column(self, identifier: Union[str, int], data) -> Iterable:
"""Slice though the data (table) and get the specified column's values.
Args:
identifier (Union[str, int]): unique identifier/index of column
data (object): the data to slice through
Returns:
Iterable: the values contained in the column requested
"""
raise NotImplementedError
[docs] @abstractmethod
def row(self, identifier, data):
"""Slice though the data (table) and get the specified row's values.
Args:
identifier (Union[str, int]): unique identifier/index of row
data (object): the data to slice through
Returns:
Iterable: the values contained in the row requested
"""
raise NotImplementedError
[docs] @abstractmethod
def nb_columns(self, data) -> int:
"""Get the number of columns that the data (table) have.
Args:
data (object): the data (table) to count its columns
Returns:
int: the number of the (data) table's columns
"""
raise NotImplementedError
[docs] @abstractmethod
def nb_rows(self, data) -> int:
"""Get the number of rows that the data (table) have.
Args:
data (object): the data (table) to count its rows
Returns:
int: the number of the (data) table's rows
"""
raise NotImplementedError
[docs] @abstractmethod
def get_numerical_attributes(self, data) -> Iterable:
r"""Get the data's attributes that represent numerical values.
Returns the attributes that fall under the Numerical Variables: either
Ratio or Interval type of variables.
Two type of numerical variables are supported:
Ratio variable:
numerical variable where all operations are supported (+, -, \*, /) and true zero is defined; eg weight.
Interval variable:
numerical variable where differences are interpretable; supported operations: [+, -]; no true zero;
eg temperature in centigrade (ie Celsius).
Args:
data (object): the data from which to retrieve the numerical attributes
Returns:
Iterable: the numerical attributes found
"""
raise NotImplementedError
[docs]class TabularIterator(ABC):
"""Iterate over the rows or columns of a table-lie data structure.
Classes implementing this interface gain the ability to iterate over the values
found in the rows or the columns of a table-like data structure.
They can also iterate over the columns indices/identifiers.
"""
[docs] @abstractmethod
def iterrows(self, data) -> Iterable:
"""Iterate over the (data) table's rows.
Get an iterable over the table's rows.
Args:
data (object): the (data) table to iterate over its rows
Returns:
Iterable: the rows of the (data) table
"""
raise NotImplementedError
[docs] @abstractmethod
def itercolumns(self, data) -> Iterable:
"""Iterate over the (data) table's columns.
Get an iterable over the table's columns.
Args:
data (object): the (data) table to iterate over its columns
Returns:
Iterable: the columns of the (data) table
"""
raise NotImplementedError
[docs] @abstractmethod
def columnnames(self, data) -> Union[Iterable[str], Iterable[int]]:
"""Iterate over data (table) column indices/identifiers.
Args:
data (object): the (data) table to iterate over its columns indices/identifiers
Returns:
Union[Iterable[str], Iterable[int]]: the column indices/identifiers of the (data) table
"""
raise NotImplementedError
[docs]class TabularMutator(ABC):
"""Mutate (alter) the contents of a table-like data structure.
Classes implementing this interface supply their instances the ability to alter the
contents of a table-like data structure.
"""
[docs] @abstractmethod
def add_column(self, *args, **kwargs):
"""Add a new column to table-like data.
Raises:
NotImplementedError: [description]
"""
raise NotImplementedError