Sorting algorithms/Insertion sort: Difference between revisions

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         l[j+1] = key</lang>
 ===Insertion sort with binary search===
-<lang python>import bisect
+<lang python>def insertion_sort_bin(seq):
-def insertion_sort_bin(seq):
     for i in range(1, len(seq)):
-        bisect.insort(seq, seq.pop(i), 0, i)</lang>
+        key = seq[i]
+        # invariant: ``seq[:i]`` is sorted
+        # find the least `low' such that ``seq[low]`` is not less then `key'.
+        #   Binary search in sorted sequence ``seq[low:up]``:
+        low, up = 0, i
+        while up > low:
+            middle = (low + up) // 2
+            if seq[middle] < key:
+                low = middle + 1
+            else:
+                up = middle
+        # insert key at position ``low``
+        seq[:] = seq[:low] + [key] + seq[low:i] + seq[i + 1:]</lang>
 =={{header|R}}==
 Direct translation of pseudocode.