# source:framspy/evolalg_steps/dissimilarity/dissimilarity.py@1185

Last change on this file since 1185 was 1185, checked in by Maciej Komosinski, 18 months ago

Renamed a module; new name is "evolalg_steps"

File size: 1.3 KB
Line
1from abc import ABC
2
3from evolalg_steps.base.step import Step
4import numpy as np
5
6
7class Dissimilarity(Step, ABC):
8
9    def __init__(self, reduction="mean", output_field="dissim", knn=None, *args, **kwargs):
10        super(Dissimilarity, self).__init__(*args, **kwargs)
11
12        self.output_field = output_field
13        self.fn_reduce = Dissimilarity.get_reduction_by_name(reduction)
14        self.knn = knn
15
16
17    @staticmethod
18    def reduce(dissim_matrix, fn_reduce, knn):
19        if fn_reduce is None:
20            return dissim_matrix
21        elif fn_reduce is Dissimilarity.knn_mean:
22            return fn_reduce(dissim_matrix, 1, knn)
23        else:
24            return fn_reduce(dissim_matrix, axis=1)
25
26
27    @staticmethod
28    def knn_mean(dissim_matrix, axis, knn):
29        return np.mean(np.partition(dissim_matrix, knn)[:, :knn], axis=axis)
30
31
32    @staticmethod
33    def get_reduction_by_name(reduction: str):
34
35        if reduction not in REDUCTION_FUNCTION:
36            raise ValueError(f"Unknown reduction type '{reduction}'. Supported: {','.join(REDUCTION_FUNCTION.keys())}")
37
38        return REDUCTION_FUNCTION[reduction]
39
40
41
42REDUCTION_FUNCTION = {
43            "mean": np.mean,
44            "max": np.max,
45            "min": np.min,
46            "sum": np.sum,
47            "knn_mean": Dissimilarity.knn_mean,
48            "none": None
49        }
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