Data commit

Task/Combinations-with-repetitions/Python/combinations-with-repetitions-1.py

@@ -0,0 +1,8 @@
+>>> from itertools import combinations_with_replacement
+>>> n, k = 'iced jam plain'.split(), 2
+>>> list(combinations_with_replacement(n,k))
+[('iced', 'iced'), ('iced', 'jam'), ('iced', 'plain'), ('jam', 'jam'), ('jam', 'plain'), ('plain', 'plain')]
+>>> # Extra credit
+>>> len(list(combinations_with_replacement(range(10), 3)))
+220
+>>>

Task/Combinations-with-repetitions/Python/combinations-with-repetitions-2.py

@@ -0,0 +1,64 @@
+'''Combinations with repetitions'''
+
+from itertools import (accumulate, chain, islice, repeat)
+from functools import (reduce)
+
+
+# combsWithRep :: Int -> [a] -> [kTuple a]
+def combsWithRep(k):
+    '''A list of tuples, representing
+       sets of cardinality k,
+       with elements drawn from xs.
+    '''
+    def f(a, x):
+        def go(ys, xs):
+            return xs + [[x] + y for y in ys]
+        return accumulate(a, go)
+
+    def combsBySize(xs):
+        return reduce(
+            f, xs, chain(
+                [[[]]],
+                islice(repeat([]), k)
+            )
+        )
+    return lambda xs: [
+        tuple(x) for x in next(islice(
+            combsBySize(xs), k, None
+        ))
+    ]
+
+
+# TEST ----------------------------------------------------
+def main():
+    '''Test the generation of sets of cardinality
+       k with elements drawn from xs.
+    '''
+    print(
+        combsWithRep(2)(['iced', 'jam', 'plain'])
+    )
+    print(
+        len(combsWithRep(3)(enumFromTo(0)(9)))
+    )
+
+
+# GENERIC -------------------------------------------------
+
+# enumFromTo :: (Int, Int) -> [Int]
+def enumFromTo(m):
+    '''Integer enumeration from m to n.'''
+    return lambda n: list(range(m, 1 + n))
+
+
+# showLog :: a -> IO String
+def showLog(*s):
+    '''Arguments printed with
+       intercalated arrows.'''
+    print(
+        ' -> '.join(map(str, s))
+    )
+
+
+# MAIN ---
+if __name__ == '__main__':
+    main()