added label mapper

image_prediction/classifier/classifier.py

@@ -5,7 +5,7 @@ import numpy as np
 from PIL.Image import Image
 
 from image_prediction.estimator.adapter.adapter import EstimatorAdapter
-from image_prediction.exceptions import UnexpectedPredictionFormat
+from image_prediction.exceptions import UnexpectedLabelFormat
 from image_prediction.utils import get_logger
 
 logger = get_logger()
@@ -25,13 +25,13 @@ class Classifier:
 
     def __validate_array_prediction_format(self, prediction):
         if not len(prediction) == len(self._classes):
-            raise UnexpectedPredictionFormat(
+            raise UnexpectedLabelFormat(
                 f"Received fewer probabilities ({len(prediction)}) than classes were specified ({len(self._classes)})."
             )
 
     def __validate_int_prediction_format(self, prediction):
         if not 0 <= prediction <= len(self._classes):
-            raise UnexpectedPredictionFormat(
+            raise UnexpectedLabelFormat(
                 f"Received class index '{prediction}' as prediction that has no associated class label."
             )
 

image_prediction/exceptions.py

@@ -14,7 +14,7 @@ class UnknownDatabaseType(ValueError):
     pass
 
 
-class UnexpectedPredictionFormat(ValueError):
+class UnexpectedLabelFormat(ValueError):
     pass
 
 

image_prediction/label_mapper/mapper.py

@@ -0,0 +1,11 @@
+import abc
+
+
+class LabelMapper(abc.ABC):
+
+    @abc.abstractmethod
+    def map_labels(self, items):
+        raise NotImplementedError
+
+    def __call__(self, items):
+        return self.map_labels(items)

image_prediction/label_mapper/mappers/numeric.py

@@ -0,0 +1,22 @@
+from typing import Mapping, Iterable
+
+from image_prediction.exceptions import UnexpectedLabelFormat
+from image_prediction.label_mapper.mapper import LabelMapper
+
+
+class IndexLabelMapper(LabelMapper):
+    def __init__(self, labels: Mapping[int, str]):
+        self.__labels = labels
+
+    def __validate_int_prediction_format(self, index_label: int) -> None:
+        if not 0 <= index_label <= len(self.__labels):
+            raise UnexpectedLabelFormat(
+                f"Received index label  '{index_label}' that has no associated string label."
+            )
+
+    def __map_label(self, index_label: int) -> str:
+        self.__validate_int_prediction_format(index_label)
+        return self.__labels[index_label]
+
+    def map_labels(self, index_labels: Iterable[int]) -> Iterable[str]:
+        return map(self.__map_label, index_labels)

test/unit_tests/conftest.py

@@ -134,8 +134,8 @@ def expected_batch_string_labels(expected_batch_numeric_labels, classes):
 
 
 @pytest.fixture
-def expected_batch_numeric_labels(input_batch, classes):
-    return random.choices(range(len(classes)), k=len(input_batch))
+def expected_batch_numeric_labels(batch_size, classes):
+    return random.choices(range(len(classes)), k=batch_size)
 
 
 @pytest.fixture

test/unit_tests/label_mapper_test.py

@@ -0,0 +1,6 @@
+from image_prediction.label_mapper.mappers.numeric import IndexLabelMapper
+
+
+def test_index_label_mapper(expected_batch_numeric_labels, expected_batch_string_labels, classes):
+    mapper = IndexLabelMapper(classes)
+    assert list(mapper(expected_batch_numeric_labels)) == expected_batch_string_labels