September Morn Update

Task/Remove-duplicate-elements/Python/remove-duplicate-elements-6.py

@@ -0,0 +1,22 @@
+from itertools import (groupby)
+
+
+# nubByKey :: (a -> b) -> [a] -> [a]
+def nubByKey(k, xs):
+    return list(list(v)[0] for _, v in groupby(sorted(xs, key=k), key=k))
+
+
+xs = [
+    'apple', 'apple',
+    'ampersand', 'aPPLE', 'Apple',
+    'orange', 'ORANGE', 'Orange', 'orange', 'apple'
+]
+for k in [
+    id,                      # default case sensitive uniqueness
+    lambda x: x.lower(),     # case-insensitive uniqueness
+    lambda x: x[0],          # unique first character (case-sensitive)
+    lambda x: x[0].lower(),  # unique first character (case-insensitive)
+]:
+    print (
+        nubByKey(k, xs)
+    )

Task/Remove-duplicate-elements/Python/remove-duplicate-elements-7.py

@@ -0,0 +1,38 @@
+# nubByEq :: (a -> a -> Bool) -> [a] -> [a]
+def nubByEq(eq, xs):
+    def go(yys, xxs):
+        if yys:
+            y = yys[0]
+            ys = yys[1:]
+            return go(ys, xxs) if (
+                elemBy(eq, y, xxs)
+            ) else (
+                [y] + go(ys, [y] + xxs)
+            )
+        else:
+            return []
+    return go(xs, [])
+
+
+# elemBy :: (a -> a -> Bool) -> a -> [a] -> Bool
+def elemBy(eq, x, xs):
+    if xs:
+        return eq(x, xs[0]) or elemBy(eq, x, xs[1:])
+    else:
+        return False
+
+
+xs = [
+    'apple', 'apple',
+    'ampersand', 'aPPLE', 'Apple',
+    'orange', 'ORANGE', 'Orange', 'orange', 'apple'
+]
+for eq in [
+    lambda a, b: a == b,                   # default case sensitive uniqueness
+    lambda a, b: a.lower() == b.lower(),   # case-insensitive uniqueness
+    lambda a, b: a[0] == b[0],             # unique first char (case-sensitive)
+    lambda a, b: a[0].lower() == b[0].lower(),   # unique first char (any case)
+]:
+    print (
+        nubByEq(eq, xs)
+    )

Task/Remove-duplicate-elements/Python/remove-duplicate-elements-8.py

@@ -0,0 +1,14 @@
+# nubBy :: (a -> a -> Bool) -> [a] -> [a]
+def nubBy(p, xs):
+    def go(xs):
+        if xs:
+            x = xs[0]
+            return [x] + go(
+                list(filter(
+                    lambda y: not p(x, y),
+                    xs[1:]
+                ))
+            )
+        else:
+            return []
+    return go(xs)