What is Polyphase Sort, Data Structure & Algorithms

Assignment Help:
One of the best known methods for external sorting on tapes is the polyphase sort.

Principle: The basic strategy of this sort is to distribute ordered initial runs of predetermined size on the available tapes and then to repeatedly merge these runs in multiple phases in which each phase has a predetermined number of merges before a new target tape is selected.

To distribute the initial runs a Fibonacci distribution is adopted. After the distribution of the runs according to Fibonacci distribution, the merging procedure is continued until the tape with the least number of run lists is empty. When this occurs the remaining working tapes are logically rotated such that the newly emptied tape becomes the new target tape and the old target tape then becomes one of the working tapes to be merged. The sort ends when all runs are merged into one.

Let the number of tapes be T and p = T - 1. The Fibonacci distribution for p = 3 is given.

Level

s
Tape
Total number of runs
1
2
3
1
0
0
1
1
2
1
1
1
3
3
1
2
2
5
4
2
3
4
9
5
4
6
7
17
6
7
11
13
31
7
13
20
24
57
8
24
37
44
105
9
44
68
81
193
Algorithm:

1. Let A be the list of N unsorted elements and R be the number of runs.

2. Let T1, T2, T3 and T4 be the tapes on which sorting is done.

3. Split the list A into R=N runs so that each run has only one element.

4. If R is not equal to perfect Fibonacci distribution then add dummy records to bring up perfect Fibonacci distribution.

5. Distribute the records in the remaining tapes according to the Fibonacci distribution.

6. Merge 3 runs, one from each tape and put into next empty tape.

7. Repeat step 6 till a single run is generated.

Related Discussions:- What is Polyphase Sort

Explain how the shuttle sort algorithm works, Question 1 Explain how th...

Question 1 Explain how the shuttle sort algorithm works by making use of the following list of integers:11, 4, 2, 8, 5, 33, 7, 3, 1, 6. Show all the steps. Question 2

Context sensitive f1 help on a field, In what ways we can get the context s...

In what ways we can get the context sensitive F1 help on a field?' Data element documentation. Data element additional text in screen painter. Using the process on help r

Avl tree, Example: (Single rotation into AVL tree, while a new node is inse...

Example: (Single rotation into AVL tree, while a new node is inserted into the AVL tree (LL Rotation)) Figure: LL Rotation The rectangles marked A, B & C are trees

Inorder traversal, Inorder traversal: The left sub tree is visited, then t...

Inorder traversal: The left sub tree is visited, then the node and then right sub-tree. Algorithm for inorder traversal is following: traverse left sub-tree visit node

Define about the inheritance hierarchy, Define about the inheritance hierar...

Define about the inheritance hierarchy Languages Eiffel and D provide constructs in language for invariants and pre- and post conditions which are compiled into the code and ar

Explain floyds algorithm, Explain Floyd's algorithm It is convenient to...

Explain Floyd's algorithm It is convenient to record the lengths of shortest paths in an n by n matrix D known as the  distance matrix: the element d ij   in the i th   row an

Implementation of stack using linked lists, In the last subsection, we have...

In the last subsection, we have implemented a stack by using an array. While a stack is implemented by using arrays, it suffers from the basic restriction of an array - i.e., its s

Define an array, Define an array. Array is made up of same data structu...

Define an array. Array is made up of same data structure that exists in any language. Array is set of same data types. Array is the collection of same elements. These same elem

Insertion of element into a linked list, ALGORITHM (Insertion of element in...

ALGORITHM (Insertion of element into a linked list) Step 1 Begin the program Step 2 if the list is empty or any new element comes before the start (head) element, then add t

Sorting algorithm is best if the list is already sorted, Which sorting algo...

Which sorting algorithm is best if the list is already sorted? Why? Insertion sort as there is no movement of data if the list is already sorted and complexity is of the order

Write Your Message!

Captcha
Free Assignment Quote

Assured A++ Grade

Get guaranteed satisfaction & time on delivery in every assignment order you paid with us! We ensure premium quality solution document along with free turntin report!

All rights reserved! Copyrights ©2019-2020 ExpertsMind IT Educational Pvt Ltd