update

Task/Range-extraction/Python/range-extraction.py

@@ -0,0 +1,28 @@
+def range_extract(lst):
+    'Yield 2-tuple ranges or 1-tuple single elements from list of increasing ints'
+    lenlst = len(lst)
+    i = 0
+    while i< lenlst:
+        low = lst[i]
+        while i <lenlst-1 and lst[i]+1 == lst[i+1]: i +=1
+        hi = lst[i]
+        if   hi - low >= 2:
+            yield (low, hi)
+        elif hi - low == 1:
+            yield (low,)
+            yield (hi,)
+        else:
+            yield (low,)
+        i += 1
+
+def printr(ranges):
+    print( ','.join( (('%i-%i' % r) if len(r) == 2 else '%i' % r)
+                     for r in ranges ) )
+
+if __name__ == '__main__':
+    for lst in [[-8, -7, -6, -3, -2, -1, 0, 1, 3, 4, 5, 7,
+                 8, 9, 10, 11, 14, 15, 17, 18, 19, 20],
+                [0, 1, 2, 4, 6, 7, 8, 11, 12, 14, 15, 16, 17, 18, 19, 20, 21, 22,
+                 23, 24, 25, 27, 28, 29, 30, 31, 32, 33, 35, 36, 37, 38, 39]]:
+        #print(list(range_extract(lst)))
+        printr(range_extract(lst))