Module type2fuzzy.membership.crispset

Classes

class CrispSet (left_val=None, right_val=None)

Implements a Crisp set

Creates a crisp set. Initially the set is empty with left and right limit values set to None

Arguments:

left_val – float, the value of the left limit right_val – float, the value of the right limit

Raises:

Exception if both limits are not None and if the left limit is greater than the right limit

Expand source code

class CrispSet:
        '''
        Implements a Crisp set
        '''
        def __init__(self, left_val=None, right_val=None):
                '''
                Creates a crisp set. Initially the set is empty with left and right 
                limit values set to None

                Arguments:
                ----------
                left_val -- float, the value of the left limit
                right_val -- float, the value of the right limit

                Raises:
                -------
                Exception if both limits are not None and if the left limit is
                greater than the right limit
                '''
                self._empty = True
                self._left_val = None
                self._right_val = None
                self._precision = 5

                if (left_val != None) and (right_val != None):
                        if left_val > right_val:
                                raise Exception('ERROR: Incorrect crisp set limits. Left')
                        self._empty= False
                        self._left_val = left_val
                        self._right_val = right_val

        @property
        def empty(self):
                '''
                Returns True if the set is empty
                '''
                return self._empty

        @property
        def left(self):
                '''
                Returns the left limit of the set
                '''
                return self._left_val

        @left.setter
        def left(self, value):
                '''
                Sets the left limit of the set. Check is bot left and right limit and sets the 
                set as not empty if both are not None
                '''

                if (self.right != None) and value != None and value > self.right:
                        raise Exception('ERROR: invalid left value')

                self._left_val = value

                if (self._left_val != None) and (self._right_val != None):
                        self._empty= False

                if (self._left_val is None) and (self._right_val is None):
                        self._empty= True

        @property
        def right(self):
                '''
                Returns the right limit of the set
                '''
                return self._right_val

        @right.setter
        def right(self, value):
                '''
                Sets the right limit of the set. Check is bot left and right limit and sets the 
                set as not empty if both are not None
                '''
                
                if (self.left != None) and value != None and value < self.left:
                        raise Exception('ERROR: invalid left value')
                
                self._right_val = value
                
                if (self._left_val != None) and (self._right_val != None):
                        self._empty= False

                if (self._left_val is None) and (self._right_val is None):
                        self._empty= True

        @property
        def mid(self):
                '''
                Computes the mid point to the crisp set.
                
                Returns:
                --------
                mid_point -- float, the crisp set mid point

                Raises:
                -------
                Exception if the set is empty
                '''

                if self.left is None or self.right is None:
                        raise Exception('ERROR: Mid point cannot be found for this set.')

                if self._empty:
                        raise Exception('ERROR: Mid point cannot be found for an empty set.')
                
                mid_point = (self._left_val+self._right_val)/2
                return mid_point

        def union(self, crisp_set):

                self._left_val = min(self._left_val, crisp_set.left)
                self._right_val = max(self._right_val, crisp_set.right)

        def __str__(self):

                dec_places_formatter = '''%0.{}f'''.format(self._precision)
                representation = ''
                if self._left_val == self._right_val:
                        representation = f'[{ dec_places_formatter % self._left_val}]'
                else:
                        representation = f'[{ dec_places_formatter % self._left_val}, {dec_places_formatter % self._right_val}]'

                return representation

        def __repr__(self):
                return f'{self.__class__.__name__}({str(self)})'

Instance variables

var empty

Returns True if the set is empty

Expand source code

@property
def empty(self):
        '''
        Returns True if the set is empty
        '''
        return self._empty

var left

Returns the left limit of the set

Expand source code

@property
def left(self):
        '''
        Returns the left limit of the set
        '''
        return self._left_val

var mid

Computes the mid point to the crisp set.

Returns:

mid_point – float, the crisp set mid point

Raises:

Exception if the set is empty

Expand source code

@property
def mid(self):
        '''
        Computes the mid point to the crisp set.
        
        Returns:
        --------
        mid_point -- float, the crisp set mid point

        Raises:
        -------
        Exception if the set is empty
        '''

        if self.left is None or self.right is None:
                raise Exception('ERROR: Mid point cannot be found for this set.')

        if self._empty:
                raise Exception('ERROR: Mid point cannot be found for an empty set.')
        
        mid_point = (self._left_val+self._right_val)/2
        return mid_point

var right

Returns the right limit of the set

Expand source code

@property
def right(self):
        '''
        Returns the right limit of the set
        '''
        return self._right_val

Methods

def union(self, crisp_set)

Expand source code

def union(self, crisp_set):

        self._left_val = min(self._left_val, crisp_set.left)
        self._right_val = max(self._right_val, crisp_set.right)