# Copyright (c) 2022 Jakub Więckowski
from .codas.ifs import ifs
from .ifs.normalization import swap_normalization
from .ifs.distance import euclidean_distance, hamming_distance
from ..helpers import rank
from .validator import Validator
[docs]
class ifCODAS():
[docs]
def __init__(self, normalization=swap_normalization, distance_1=euclidean_distance, distance_2=hamming_distance, tau=0.05):
"""
Create Intuitionistic Fuzzy CODAS method object with normalization function and distances metrics
Parameters
----------
normalization: callable, default=swap_normalization
Function used to calculate normalized decision matrix
distance_1: callable, default=euclidean_distance
Function used to calculate distance between two IFS
distance_2: callable, default=hamming_distance
Function used to calculate distance between two IFS
tau: float, default=0.05
Threshold parameter
"""
self.normalization = normalization
self.distance_1 = distance_1
self.distance_2 = distance_2
self.tau = tau
self.__descending = True
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def __call__(self, matrix, weights, types):
"""
Calculates the alternatives preferences
Parameters
----------
matrix : ndarray
Decision matrix / alternatives data.
Alternatives are in rows and Criteria are in columns.
weights : ndarray
Vector of criteria weights in a crisp or Intuitionistic Fuzzy form
types : ndarray
Types of criteria, 1 profit, -1 cost.
Criteria types cannot be all profit or all cost.
Returns
----------
ndarray:
Preference calculated for alternatives. Greater values are placed higher in ranking
"""
# validate data
Validator.ifs_validation(matrix, weights, types, mixed_types=True)
self.preferences = ifs(matrix, weights, types, self.normalization, self.distance_1, self.distance_2, self.tau).astype(float)
return self.preferences
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def rank(self):
"""
Calculates the alternatives ranking based on the obtained preferences
Returns
----------
ndarray:
Ranking of alternatives
"""
try:
return rank(self.preferences, self.__descending)
except AttributeError:
raise AttributeError('Cannot calculate ranking before assessment')
except:
raise ValueError('Error occurred in ranking calculation')