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_match_powers_of_base.py b/contrib/experimental/great_expectations_experimental/expectations/expect_column_values_to_match_powers_of_base.py
new file mode 100644
--- /dev/null
+++ b/contrib/experimental/great_expectations_experimental/expectations/expect_column_values_to_match_powers_of_base.py
@@ -0,0 +1,245 @@
+"""
+This is a template for creating custom ColumnMapExpectations.
+For detailed instructions on how to use it, please see:
+    https://docs.greatexpectations.io/docs/guides/expectations/creating_custom_expectations/how_to_create_custom_column_map_expectations
+"""
+
+import math
+from typing import Optional
+
+from great_expectations.core.expectation_configuration import ExpectationConfiguration
+from great_expectations.exceptions import InvalidExpectationConfigurationError
+from great_expectations.execution_engine import PandasExecutionEngine
+from great_expectations.expectations.expectation import ColumnMapExpectation
+from great_expectations.expectations.metrics import (
+    ColumnMapMetricProvider,
+    column_condition_partial,
+)
+
+
+# This method checks to see if the given num is a power of base.
+# For example: 32 is a power of 2 since 2^5 = 32.
+def is_power_of_n(num, base) -> bool:
+    if base in {0, 1}:
+        return num == base
+    power = int(math.log(num, base) + 0.5)
+    return base**power == num
+
+
+# This class defines a Metric to support your Expectation.
+# For most ColumnMapExpectations, the main business logic for calculation will live in this class.
+class ColumnValuesMatchPowersOfBase(ColumnMapMetricProvider):
+    # This is the id string that will be used to reference your metric.
+    condition_metric_name = "column_values.match_powers_of_base"
+    condition_value_keys = ("base_integer",)
+
+    # This method implements the core logic for the PandasExecutionEngine
+    @column_condition_partial(engine=PandasExecutionEngine)
+    def _pandas(cls, column, base_integer, **kwargs):
+        return column.apply(lambda x: is_power_of_n(x, base_integer))
+
+
+# This class defines the Expectation itself
+class ExpectColumnValuesToMatchPowersOfBase(ColumnMapExpectation):
+    """Expect column values to match powers of Base (Base ** power == column value)"""
+
+    # These examples will be shown in the public gallery.
+    # They will also be executed as unit tests for your Expectation.
+    examples = [
+        {
+            "data": {
+                "mostly_powers_of_two_but_one": [
+                    1,
+                    2,
+                    4,
+                    8,
+                    16.0,
+                    11,
+                    67108864,
+                    32.00,
+                    64,
+                    128,
+                    256,
+                    512,
+                    1024,
+                    128,
+                ],
+                "all_powers_of_3": [
+                    59049,
+                    1,
+                    3,
+                    729,
+                    1594323,
+                    81,
+                    27,
+                    243,
+                    9,
+                    177147,
+                    531441,
+                    2187,
+                    6561,
+                    19683,
+                ],
+                "all_powers_of_2_increasing_order": [
+                    1,
+                    2,
+                    4,
+                    8,
+                    16,
+                    32,
+                    64,
+                    128,
+                    256,
+                    512,
+                    1024,
+                    2048,
+                    4096,
+                    8192,
+                ],
+                "all_powers_of_7": [
+                    1,
+                    49,
+                    678223072849,
+                    7,
+                    4747561509943,
+                    343,
+                    823543,
+                    2401,
+                    40353607,
+                    96889010407,
+                    16807,
+                    4747561509943,
+                    1628413597910449,
+                    40353607,
+                ],
+            },
+            "tests": [
+                {
+                    "title": "positive_test_with_mostly_powers_of_two_but_one",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {
+                        "column": "mostly_powers_of_two_but_one",
+                        "base_integer": 2,
+                        "mostly": 0.8,
+                    },
+                    "out": {
+                        "success": True,
+                        "unexpected_index_list": [5],
+                        "unexpected_list": [11],
+                    },
+                },
+                {
+                    "title": "positive_test_with_all_powers_of_3",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {"column": "all_powers_of_3", "base_integer": 3},
+                    "out": {
+                        "success": True,
+                        "unexpected_index_list": [],
+                        "unexpected_list": [],
+                    },
+                },
+                {
+                    "title": "positive_test_with_all_powers_of_7",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {
+                        "column": "all_powers_of_7",
+                        "base_integer": 7,
+                        "mostly": 0.3,
+                    },
+                    "out": {
+                        "success": True,
+                        "unexpected_index_list": [],
+                        "unexpected_list": [],
+                    },
+                },
+                {
+                    "title": "positive_test_with_all_powers_of_2_increasing_order",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {
+                        "column": "all_powers_of_2_increasing_order",
+                        "base_integer": 2,
+                        "mostly": 1,
+                    },
+                    "out": {
+                        "success": True,
+                        "unexpected_index_list": [],
+                        "unexpected_list": [],
+                    },
+                },
+                {
+                    "title": "negative_test_with_powers_of_two",
+                    "exact_match_out": False,
+                    "include_in_gallery": True,
+                    "in": {
+                        "column": "mostly_powers_of_two_but_one",
+                        "base_integer": 2,
+                        "mostly": 1,
+                    },
+                    "out": {
+                        "success": False,
+                        "unexpected_index_list": [5],
+                        "unexpected_list": [11],
+                    },
+                },
+            ],
+        }
+    ]
+
+    # 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.match_powers_of_base"
+
+    # This is a list of parameter names that can affect whether the Expectation evaluates to True or False
+    success_keys = (
+        "base_integer",
+        "mostly",
+    )
+
+    # This dictionary contains default values for any parameters that should have default values
+    default_kwarg_values = {"mostly": 1}
+
+    def validate_configuration(
+        self, configuration: Optional[ExpectationConfiguration]
+    ) -> None:
+        """
+        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:
+            None. Raises InvalidExpectationConfigurationError if the config is not validated successfully
+        """
+
+        super().validate_configuration(configuration)
+        if configuration is None:
+            configuration = self.configuration
+
+        base_integer = configuration.kwargs["base_integer"]
+
+        # # Check other things in configuration.kwargs and raise Exceptions if needed
+        try:
+            # Base cannot be less than zero,
+            # Base must be an Integer
+            assert base_integer is None or isinstance(base_integer, int)
+            assert base_integer >= 0
+        except AssertionError as e:
+            raise InvalidExpectationConfigurationError(str(e))
+
+    # This object contains metadata for display in the public Gallery
+    library_metadata = {
+        "maturity": "beta",  # "experimental", "beta", or "production"
+        "tags": ["beta"],  # Tags for this Expectation in the Gallery
+        "contributors": [  # GitHub handles for all contributors to this Expectation.
+            "@rifatKomodoDragon",  # Don't forget to add your GitHub handle here!
+        ],
+    }
+
+
+if __name__ == "__main__":
+    ExpectColumnValuesToMatchPowersOfBase().print_diagnostic_checklist()


Test patch: