[tf-legacy] Employ a fallback str2bool mapping from the feature column's distinct values when the feature's values aren't boolean-like.

ludwig/features/binary_feature.py

@@ -60,6 +60,7 @@ class BinaryFeatureMixin:
         },
         "fill_value": fill_value_schema,
         "computed_fill_value": fill_value_schema,
+        "fallback_true_label": {'type': 'string'},
     }
 
     @staticmethod
@@ -80,14 +81,25 @@ def get_feature_meta(column, preprocessing_parameters, backend):
                 f"found: {distinct_values.values.tolist()}"
             )
 
-        str2bool = {v: strings_utils.str2bool(v) for v in distinct_values}
-        bool2str = [
-            k for k, v in sorted(str2bool.items(), key=lambda item: item[1])
-        ]
+            if 'fallback_true_label' in preprocessing_parameters:
+                fallback_true_label = preprocessing_parameters['fallback_true_label']
+            else:
+                fallback_true_label = sorted(distinct_values)[0]
+                logger.warning(
+                    f"In case binary feature {column.name} doesn't have conventional boolean values, "
+                    f"we will interpret {fallback_true_label} as 1 and the other values as 0. "
+                    f"If this is incorrect, please use the category feature type or "
+                    f"manually specify the true value with `preprocessing.fallback_true_label`.")
+
+            str2bool = {v: strings_utils.str2bool(
+                v, fallback_true_label) for v in distinct_values}
+            bool2str = [k for k, v in sorted(
+                str2bool.items(), key=lambda item: item[1])]
 
         return {
             "str2bool": str2bool,
             "bool2str": bool2str,
+            "fallback_true_label": fallback_true_label
         }
 
     @staticmethod

ludwig/utils/strings_utils.py

@@ -65,8 +65,23 @@ def strip_accents(s):
                    if unicodedata.category(c) != 'Mn')
 
 
-def str2bool(v):
-    return str(v).lower() in BOOL_TRUE_STRS
+def str2bool(v, fallback_true_label=None):
+    """Returns bool representation of the given value v.
+    Check the value against global bool string lists.
+    Fallback to using fallback_true_label as True if the value isn't in the global bool string lists.
+    args:
+        v: Value to get the bool representation for.
+        fallback_true_label: (str) label to use as 'True'.
+    """
+    v_str = str(v).lower()
+    if v_str in BOOL_TRUE_STRS:
+        return True
+    if v_str in BOOL_FALSE_STRS:
+        return False
+    if fallback_true_label is None:
+        raise ValueError(
+            f'Cannot automatically map value {v} to a boolean and no `fallback_true_label` specified.')
+    return v == fallback_true_label
 
 
 def match_replace(string_to_match, list_regex):
@@ -149,7 +164,8 @@ def create_vocabulary(
     elif vocab_file is not None:
         vocab = load_vocabulary(vocab_file)
 
-    processed_lines = data.map(lambda line: tokenizer(line.lower() if lowercase else line))
+    processed_lines = data.map(lambda line: tokenizer(
+        line.lower() if lowercase else line))
     processed_counts = processed_lines.explode().value_counts(sort=False)
     processed_counts = processor.compute(processed_counts)
     unit_counts = Counter(dict(processed_counts))

tests/ludwig/utils/test_strings_utils.py

@@ -0,0 +1,24 @@
+import pytest
+
+from ludwig.utils import strings_utils
+
+
+def test_str_to_bool():
+    # Global bool mappings are used.
+    assert strings_utils.str2bool('True') == True
+    assert strings_utils.str2bool('true') == True
+    assert strings_utils.str2bool('0') == False
+
+    # Error raised if non-mapped value is encountered and no fallback is specified.
+    with pytest.raises(Exception):
+        strings_utils.str2bool('bot')
+
+    # Fallback label is used.
+    assert strings_utils.str2bool('bot', fallback_true_label='bot') == True
+    assert strings_utils.str2bool('human', fallback_true_label='bot') == False
+    assert strings_utils.str2bool('human', fallback_true_label='human') == True
+    assert strings_utils.str2bool(
+        'human', fallback_true_label='Human') == False
+
+    # Fallback label is used, strictly as a fallback.
+    assert strings_utils.str2bool('True', fallback_true_label='False') == True