Coverage for src/sensai/data_transformation/value_transformation.py: 32%

1from typing import Sequence, Any 

2 

3import numpy as np 

4 

5 

6class ValueOneHotEncoder: 

7 """ 

8 A simple one-hot encoder, which encodes individual values. 

9 A one-hot encoder transforms a categorical input value into an array whose length is the number of categories where all values 

10 are zero except one whose value is one, indicating the category that is active. 

11 """ 

12 def __init__(self, ignore_unknown=True): 

13 """ 

14 :param ignore_unknown: whether unknown input values (not seen during fit) shall be ignored, resulting in an array of zeroes; 

15 if False, throw an exception instead 

16 """ 

17 self.categories = None 

18 self.category2index = None 

19 self.ignoreUnknown = ignore_unknown 

20 

21 def fit(self, values: Sequence[Any]): 

22 unique_values = np.unique(values) 

23 self.categories = sorted(unique_values) 

24 self.category2index = {category: idx for idx, category in enumerate(self.categories)} 

25 

26 def transform(self, value) -> np.ndarray: 

27 a = np.zeros(len(self.categories)) 

28 category_idx = self.category2index.get(value) 

29 if category_idx is None: 

30 if not self.ignoreUnknown: 

31 raise Exception(f"Got unknown value '{value}'") 

32 else: 

33 a[category_idx] = 1.0 

34 return a