python/luhn: 1st iteration

python/README.md

@@ -44,3 +44,4 @@
 - [roman-numerals](./roman-numerals/README.md)
 - [scrabble-score](./scrabble-score/README.md)
 - [difference-of-squares](./difference-of-squares/README.md)
+- [luhn](./luhn/README.md)

python/luhn/.coverage

@@ -0,0 +1 @@
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python/luhn/.coverage.xml

@@ -0,0 +1,65 @@
+<?xml version="1.0" ?>
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+	<!-- Generated by coverage.py: https://coverage.readthedocs.io -->
+	<!-- Based on https://raw.githubusercontent.com/cobertura/web/master/htdocs/xml/coverage-04.dtd -->
+	<sources>
+		<source>/home/vpayno/git_vpayno/exercism-workspace/python/luhn</source>
+	</sources>
+	<packages>
+		<package branch-rate="0.9" complexity="0" line-rate="0.9737" name=".">
+			<classes>
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+</coverage>

python/luhn/.coveragerc

@@ -0,0 +1,2 @@
+[run]
+omit = __init__.py, *_test.py

python/luhn/.pylintrc

@@ -0,0 +1 @@
+../.pylintrc

python/luhn/README.md

@@ -97,4 +97,9 @@ Sum the digits
 
 ### Based on
 
-The Luhn Algorithm on Wikipedia - https://en.wikipedia.org/wiki/Luhn_algorithm
+The Luhn Algorithm on Wikipedia - https://en.wikipedia.org/wiki/Luhn_algorithm
+
+### My Solution
+
+- [my solution](./luhn.py)
+- [run-tests](./run-tests-python.txt)

python/luhn/luhn.py

@@ -1,6 +1,198 @@
-class Luhn:
-    def __init__(self, card_num):
-        pass
+"""Python Luhn Exercism"""
 
-    def valid(self):
-        pass
+import re
+from itertools import chain
+
+
+class String(str):
+    """Extending String class/type"""
+
+    def match(self, regex: str) -> bool:
+        """Does the String match a regex?
+
+        >>> s: String = String("1234 5678")
+        >>> s
+        '1234 5678'
+        >>> s.match(r"^[0-9 ]+$")
+        True
+        >>> s.match(r"^[a-z ]+$")
+        False
+
+        :param regex: rstr
+        :return: bool
+        """
+
+        return bool(re.match(regex, self))
+
+    def extract_digits(self) -> list[int]:
+        """Extracts digits from a code.
+
+        >>> s: String = String("1234 5678")
+        >>> s.extract_digits()
+        [1, 2, 3, 4, 5, 6, 7, 8]
+
+        :return: list[int]
+        """
+
+        def is_digit(rune: str) -> bool:
+            """Test function for filter.
+
+            >>> is_digit("a")
+            False
+            >>> is_digit("7")
+            True
+
+            :return: True if rune is a digit
+            """
+
+            return rune.isdigit()
+
+        filtered = filter(is_digit, list(self))
+
+        return [int(r) for r in filtered]
+
+
+class Luhn:  # pylint: disable=too-few-public-methods
+    """Determine if a number is a valid Luhn number."""
+
+    def __init__(self, card_num: str) -> None:
+        self.code: String = String(card_num.strip())
+
+    def valid(self) -> bool:
+        """Is this a valid Luhn number?
+
+        >>> l: Luhn = Luhn("055 444 285")
+        >>> l.valid()
+        True
+        >>> l: Luhn = Luhn("055 444 286")
+        >>> l.valid()
+        False
+        >>> l: Luhn = Luhn("234 567 891 234")
+        >>> l.valid()
+        True
+        >>> n: String = String("234 567 891 234")
+        >>> n == "0"
+        False
+        >>> len(n) == 0
+        False
+        >>> n == "0"
+        False
+        >>> n.match(r"^([0-9 ])+$")
+        True
+
+        :return: bool
+        """
+
+        if (
+            self.code == "0"
+            or len(self.code) == 0
+            or not self.code.match(r"^([0-9 ])+$")
+        ):
+            return False
+
+        return self.__is_luhn_number()
+
+    def __is_luhn_number(self) -> bool:
+        """Is the code a valid luhn number?
+
+        >>> l: Luhn = Luhn("055 444 285")
+        >>> l._Luhn__is_luhn_number()
+        True
+        >>> l: Luhn = Luhn("055 444 286")
+        >>> l._Luhn__is_luhn_number()
+        False
+        >>> digits: list[int] = l.code.extract_digits()
+        >>> digits
+        [0, 5, 5, 4, 4, 4, 2, 8, 6]
+        >>> numbers: list[int] = l._Luhn__step_one_and_two(digits)
+        >>> numbers
+        [1, 5, 8, 4, 8, 2, 7, 6, 0]
+        >>> digit_sum: int = sum(numbers)
+        >>> digit_sum
+        41
+        >>> l: Luhn = Luhn("234 567 891 234")
+        >>> l._Luhn__is_luhn_number()
+        True
+        >>> digits: list[int] = l.code.extract_digits()
+        >>> digits
+        [2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4]
+        >>> numbers: list[int] = l._Luhn__step_one_and_two(digits)
+        >>> numbers
+        [4, 3, 8, 5, 3, 7, 7, 9, 2, 2, 6, 4]
+        >>> digit_sum: int = sum(numbers)
+        >>> digit_sum
+        60
+
+        :return: bool
+        """
+
+        digits: list[int] = self.code.extract_digits()
+
+        numbers: list[int] = self.__step_one_and_two(digits)
+
+        digit_sum: int = sum(numbers)
+
+        return (digit_sum % 10) == 0
+
+    def __step_one_and_two(self, digits: list[int]) -> list[int]:
+        """Performs steps one and two of the luhn number verification algorithm.
+
+        >>> l: Luhn = Luhn("0123456789")
+        >>> d: list[int] = l.code.extract_digits()
+        >>> d
+        [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
+        >>> l._Luhn__step_one_and_two(d)
+        [0, 1, 4, 3, 8, 5, 3, 7, 7, 9]
+        >>> l: Luhn = Luhn("59")
+        >>> d: list[int] = l.code.extract_digits()
+        >>> d
+        [5, 9]
+        >>> s = l._Luhn__step_one_and_two(d)
+        >>> s
+        [1, 9]
+        >>> sum(s)
+        10
+        >>> l: Luhn = Luhn(" 0")
+        >>> d: list[int] = l.code.extract_digits()
+        >>> d
+        [0]
+        >>> l._Luhn__step_one_and_two(d)
+        [0]
+        >>> sum(l._Luhn__step_one_and_two(d))
+        0
+        >>> l: Luhn = Luhn("234 567 891 234")
+        >>> d: list[int] = l.code.extract_digits()
+        >>> d
+        [2, 3, 4, 5, 6, 7, 8, 9, 1, 2, 3, 4]
+        >>> l._Luhn__step_one_and_two(d)
+        [4, 3, 8, 5, 3, 7, 7, 9, 2, 2, 6, 4]
+        >>> sum(l._Luhn__step_one_and_two(d))
+        57
+
+        :return: list[int]
+        """
+
+        digits.reverse()
+
+        even: list[int] = digits[0::2]
+        odd: list[int] = digits[1::2]
+
+        new_odd: list[int] = []
+
+        for n in odd:
+            n *= 2
+
+            if n > 9:
+                n -= 9
+
+            new_odd.append(n)
+
+        # flatten the list of tuples
+        new_list: list[int] = list(chain.from_iterable(zip(even, new_odd)))
+
+        new_list.reverse()
+
+        if len(even) != len(odd):
+            new_list.append(even[-1])
+
+        return new_list