Code for Shell Sort in Python

Competitive Coding/Sorting/Shell_Sort/shellsort.py

@@ -0,0 +1,29 @@
+"""
+The algorithm uses a procedure called Shell Sort
+to sort the lists. It breaks the list to smaller sublists
+and each sublist is further sorted by insertion sort.
+The sublists are made using a gap and elements at gap i
+is often selected and forms a sublist.
+"""
+
+def shellSort(test):
+    sublistcount = len(test)//2 #Finds gap to create sublists
+    while(sublistcount > 0):
+	for startposition in range(sublistcount):
+		gapInsertionSort(test,startposition,sublistcount)
+	print("After increments of size",sublistcount,"The list is",test)
+	sublistcount = sublistcount // 2
+
+def gapInsertionSort(test,start,gap):
+	for i in range(start+gap,len(test),gap):
+		currentvalue = test[i]
+		position = i
+		while(position>=gap and test[position-gap]>currentvalue):
+			test[position]=test[position-gap]
+			position = position-gap
+		test[position]=currentvalue
+
+if __name__=="__main__":
+    test = [99,109,29,89,44,98,20,55,31]
+    shellSort(test)
+    print test