template decorator

README.md

@@ -282,6 +282,22 @@ def RECENCY() -> Column:
     return F.months_between(F.lit(rfm.FeatureMaker.make_date), F.col("DATE"))
 ```
 
+#### @template
+Provides an option to pass a template string that's to be used to create a text feature, this template is saved in [metadata](#metadata).
+
+```python
+import pyspark.sql.functions as F
+import rialto.maker as rfm
+from pyspark.sql import Column
+from rialto.metadata import ValueType as VT
+
+@rfm.feature(VT.numerical)
+@rfm.desc("Age of customer")
+@rfm.template("Customer is $X years old")
+def AGE() -> Column:
+    return F.col("AGE")
+```
+
 #### @param
 Inspired by @pytest.mark.parametrize, it has similar interface and fulfills the same role. It allows you to invoke the feature function multiple times with different values of the parameter.
 If multiple @params are used, the number of final features will be a product of all parameters. The feature function has to expect a parameter with the same name as the @params name.

rialto/maker/containers.py

@@ -33,6 +33,7 @@ def __init__(self, name: str, callable_object: typing.Callable, value_type: Valu
         self.dependencies: typing.List[str] = []
         self.type = value_type
         self.description = "basic feature"
+        self.template = "value $X"
 
     def __str__(self) -> str:
         """
@@ -44,7 +45,8 @@ def __str__(self) -> str:
             f"Name: {self.name}\n\t"
             f"Parameters: {self.parameters}\n\t"
             f"Type: {self.get_type()}\n\t"
-            f"Description: {self.description}"
+            f"Description: {self.description}\n\t"
+            f"Template: {self.template}"
         )
 
     def metadata(self) -> FeatureMetadata:
@@ -53,7 +55,9 @@ def metadata(self) -> FeatureMetadata:
 
         :return: metadata dict
         """
-        return FeatureMetadata(name=self.get_feature_name(), value_type=self.type, description=self.description)
+        return FeatureMetadata(
+            name=self.get_feature_name(), value_type=self.type, description=self.description, template=self.template
+        )
 
     def get_feature_name(self) -> str:
         """

rialto/maker/wrappers.py

@@ -12,7 +12,7 @@
 #  See the License for the specific language governing permissions and
 #  limitations under the License.
 
-__all__ = ["feature", "desc", "param", "depends"]
+__all__ = ["feature", "desc", "template", "param", "depends"]
 
 import typing
 from copy import deepcopy
@@ -89,7 +89,7 @@ def desc(feature_functions: typing.Union[typing.Callable, FeatureHolder], desc:
     Wrap feature with string description, used in metadata
 
     :param feature_functions: FeatureHolder or pure function
-    :param type: FeatureType enum (numerical, ordinal, nominal)
+    :param desc: text description of the feature
     :return: FeatureHolder
     """
     logger.trace(f"Wrapping {feature_functions} with description")
@@ -109,6 +109,32 @@ def wrapper() -> FeatureHolder:
     return wrapper()
 
 
+@decorator_with_args
+def template(feature_functions: typing.Union[typing.Callable, FeatureHolder], template: str):
+    """
+    Wrap feature with string template to create a text feature
+
+    :param feature_functions: FeatureHolder or pure function
+    :param template: string template of the feature
+    :return: FeatureHolder
+    """
+    logger.trace(f"Wrapping {feature_functions} with text template")
+
+    def wrapper() -> FeatureHolder:
+        if isinstance(feature_functions, FeatureHolder):
+            for f in feature_functions:
+                f.template = template
+            return feature_functions
+        else:
+            func_list = FeatureHolder()
+            new_feature_f = FeatureFunction(feature_functions.__name__, feature_functions)
+            new_feature_f.template = template
+            func_list.append(new_feature_f)
+            return func_list
+
+    return wrapper()
+
+
 @decorator_with_args
 def param(feature_functions: typing.Union[typing.Callable, FeatureHolder], parameter_name: str, values: typing.List):
     """

rialto/metadata/data_classes/feature_metadata.py

@@ -31,14 +31,16 @@ class FeatureMetadata:
     value_type: ValueType
     name: str
     description: str
+    template: str = None
     group: GroupMetadata = None
 
     def __repr__(self) -> str:
         """Serialize object to string"""
         return (
             "FeatureMetadata("
             f"name={self.name!r}, value_type={self.value_type!r}, "
-            f"description={self.description!r}, group={self.group!r}, "
+            f"description={self.description!r}, template={self.template!r}, "
+            f"group={self.group!r}"
             ")"
         )
 
@@ -49,7 +51,7 @@ def to_tuple(self, group_name: str) -> Tuple:
         :param group_name: Feature group name
         :return: tuple with feature information
         """
-        return (self.name, self.value_type.value, self.description, group_name)
+        return (self.name, self.value_type.value, self.description, self.template, group_name)
 
     def add_group(self, group: GroupMetadata) -> Self:
         """
@@ -73,4 +75,5 @@ def from_spark(cls, record: Row) -> Self:
             value_type=ValueType[record.feature_type],
             name=record.feature_name,
             description=record.feature_description,
+            template=record.feature_template,
         )

tests/maker/test_FeatureFunction.py

@@ -57,8 +57,8 @@ def test_serialization():
     func.parameters["paramC"] = 1
     func.parameters["paramA"] = 4
     assert (
-        func.__str__()
-        == "Name: feature\n\tParameters: {'paramC': 1, 'paramA': 4}\n\tType: nominal\n\tDescription: basic feature"
+        func.__str__() == "Name: feature\n\tParameters: {'paramC': 1, 'paramA': 4}\n\t"
+        "Type: nominal\n\tDescription: basic feature\n\tTemplate: value $X"
     )
 
 
@@ -68,7 +68,9 @@ def test_metadata():
     func.parameters["paramA"] = 4
     func.dependencies = ["featureB", "featureC"]
     func.description = "nice feature"
+    func.template = "value $X something"
 
     assert func.metadata().name == "FEATURE_PARAMA_4_PARAMC_1"
     assert func.metadata().value_type == ValueType.ordinal
     assert func.metadata().description == "nice feature"
+    assert func.metadata().template == "value $X something"

tests/metadata/resources.py

@@ -31,6 +31,7 @@
         StructField("feature_name", StringType(), True),
         StructField("feature_type", StringType(), True),
         StructField("feature_description", StringType(), True),
+        StructField("feature_template", StringType(), True),
         StructField("group_name", StringType(), True),
     ]
 )
@@ -41,8 +42,8 @@
 ]
 
 feature_base = [
-    ("Feature1", "nominal", "feature1", "Group2"),
-    ("Feature2", "nominal", "feature2", "Group2"),
+    ("Feature1", "nominal", "feature1", "template1", "Group2"),
+    ("Feature2", "nominal", "feature2", "template2", "Group2"),
 ]
 
 group_md1 = GroupMetadata(
@@ -64,4 +65,6 @@
     features=["Feature1", "Feature2"],
 )
 
-feature_md1 = FeatureMetadata(name="Feature1", value_type=ValueType.nominal, description="feature1", group=group_md2)
+feature_md1 = FeatureMetadata(
+    name="Feature1", value_type=ValueType.nominal, description="feature1", template="template1", group=group_md2
+)