Repository: great-expectations/great_expectations

Issue:
Use cleaner solution for non-truncating division in python 2
Prefer `from __future__ import division` to `1.*x/y`


Discussion:
Done inline during improve_partitions push.

Resolving patch:
diff --git a/contrib/experimental/great_expectations_experimental/expectations/expect_column_values_to_be_valid_iana_timezone.py b/contrib/experimental/great_expectations_experimental/expectations/expect_column_values_to_be_valid_iana_timezone.py
new file mode 100644
--- /dev/null
+++ b/contrib/experimental/great_expectations_experimental/expectations/expect_column_values_to_be_valid_iana_timezone.py
@@ -0,0 +1,152 @@
+import json
+from typing import Optional
+
+import pytz
+
+from great_expectations.core.expectation_configuration import ExpectationConfiguration
+from great_expectations.exceptions import InvalidExpectationConfigurationError
+from great_expectations.execution_engine import (
+    PandasExecutionEngine,
+    SparkDFExecutionEngine,
+    SqlAlchemyExecutionEngine,
+)
+from great_expectations.expectations.expectation import ColumnMapExpectation
+from great_expectations.expectations.metrics import (
+    ColumnMapMetricProvider,
+    column_condition_partial,
+)
+from great_expectations.expectations.metrics.import_manager import F, sparktypes
+
+
+def is_valid_timezone(timezone: str) -> bool:
+    try:
+        pytz.timezone(timezone)
+        return True
+    except pytz.UnknownTimeZoneError:
+        return False
+
+
+# This class defines a Metric to support your Expectation.
+# For most ColumnMapExpectations, the main business logic for calculation will live in this class.
+class ColumnValuesIanaTimezone(ColumnMapMetricProvider):
+
+    # This is the id string that will be used to reference your metric.
+    condition_metric_name = "column_values.iana_timezone"
+
+    # This method implements the core logic for the PandasExecutionEngine
+    @column_condition_partial(engine=PandasExecutionEngine)
+    def _pandas(cls, column, **kwargs):
+
+        return column.apply(lambda x: is_valid_timezone(x))
+
+    # This method defines the business logic for evaluating your metric when using a SqlAlchemyExecutionEngine
+    # @column_condition_partial(engine=SqlAlchemyExecutionEngine)
+    # def _sqlalchemy(cls, column, _dialect, **kwargs):
+    #     raise NotImplementedError
+
+    # This method defines the business logic for evaluating your metric when using a SparkDFExecutionEngine
+    @column_condition_partial(engine=SparkDFExecutionEngine)
+    def _spark(cls, column, **kwargs):
+
+        tz_udf = F.udf(is_valid_timezone, sparktypes.BooleanType())
+
+        return tz_udf(column)
+
+
+# This class defines the Expectation itself
+class ExpectColumnValuesToBeValidIanaTimezone(ColumnMapExpectation):
+    """Expect values in this column to be valid IANA timezone strings.
+    A full list of valid timezones can be viewed by `pytz.all_timezones`.
+    See https://www.iana.org/time-zones for more information.
+    """
+
+    # These examples will be shown in the public gallery.
+    # They will also be executed as unit tests for your Expectation.
+    examples = [
+        {
+            "data": {
+                "valid_timezones": [
+                    "UTC",
+                    "America/New_York",
+                    "Australia/Melbourne",
+                    "US/Hawaii",
+                    "Africa/Sao_Tome",
+                ],
+                "invalid_timezones": [
+                    "America/Calgary",
+                    "Europe/Nice",
+                    "New York",
+                    "Central",
+                    "+08:00",
+                ],
+            },
+            "tests": [
+                {
+                    "title": "positive_test_with_timezones",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {"column": "valid_timezones"},
+                    "out": {"success": True},
+                },
+                {
+                    "title": "negative_test_with_timezones",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {"column": "invalid_timezones"},
+                    "out": {"success": False},
+                },
+            ],
+        }
+    ]
+
+    # This is the id string of the Metric used by this Expectation.
+    # For most Expectations, it will be the same as the `condition_metric_name` defined in your Metric class above.
+    map_metric = "column_values.iana_timezone"
+
+    # This is a list of parameter names that can affect whether the Expectation evaluates to True or False
+    success_keys = ("mostly",)
+
+    # This dictionary contains default values for any parameters that should have default values
+    default_kwarg_values = {}
+
+    def validate_configuration(self, configuration: Optional[ExpectationConfiguration]):
+        """
+        Validates that a configuration has been set, and sets a configuration if it has yet to be set. Ensures that
+        necessary configuration arguments have been provided for the validation of the expectation.
+
+        Args:
+            configuration (OPTIONAL[ExpectationConfiguration]): \
+                An optional Expectation Configuration entry that will be used to configure the expectation
+        Returns:
+            True if the configuration has been validated successfully. Otherwise, raises an exception
+        """
+
+        super().validate_configuration(configuration)
+        if configuration is None:
+            configuration = self.configuration
+
+        # # Check other things in configuration.kwargs and raise Exceptions if needed
+        # try:
+        #     assert (
+        #         ...
+        #     ), "message"
+        #     assert (
+        #         ...
+        #     ), "message"
+        # except AssertionError as e:
+        #     raise InvalidExpectationConfigurationError(str(e))
+
+        return True
+
+    # This object contains metadata for display in the public Gallery
+    library_metadata = {
+        "tags": ["type-entities", "hackathon", "timezone"],
+        "contributors": [
+            "@lucasasmith",
+        ],
+        "requirements": ["pytz"],
+    }
+
+
+if __name__ == "__main__":
+    ExpectColumnValuesToBeValidIanaTimezone().print_diagnostic_checklist()


Test patch: