Data commit

Task/ISBN13-check-digit/Python/isbn13-check-digit-1.py

@@ -0,0 +1,16 @@
+def is_isbn13(n):
+    n = n.replace('-','').replace(' ', '')
+    if len(n) != 13:
+        return False
+    product = (sum(int(ch) for ch in n[::2])
+               + sum(int(ch) * 3 for ch in n[1::2]))
+    return product % 10 == 0
+
+if __name__ == '__main__':
+    tests = '''
+978-1734314502
+978-1734314509
+978-1788399081
+978-1788399083'''.strip().split()
+    for t in tests:
+        print(f"ISBN13 {t} validates {is_isbn13(t)}")

Task/ISBN13-check-digit/Python/isbn13-check-digit-2.py

@@ -0,0 +1,41 @@
+'''ISBN13 check digit'''
+
+
+from itertools import cycle
+
+
+# isISBN13 :: String -> Bool
+def isISBN13(s):
+    '''True if s is a valid ISBN13 string
+    '''
+    digits = [int(c) for c in s if c.isdigit()]
+    return 13 == len(digits) and (
+        0 == sum(map(
+            lambda f, x: f(x),
+            cycle([
+                lambda x: x,
+                lambda x: 3 * x
+            ]),
+            digits
+        )) % 10
+    )
+
+
+# ------------------------- TEST -------------------------
+# main :: IO ()
+def main():
+    '''Test strings for ISBN-13 validity.'''
+
+    print('\n'.join(
+        repr((s, isISBN13(s))) for s
+        in ["978-1734314502",
+            "978-1734314509",
+            "978-1788399081",
+            "978-1788399083"
+            ]
+    ))
+
+
+# MAIN ---
+if __name__ == '__main__':
+    main()