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

Queue, algorithm for insertion in a queue using pointers

algorithm for insertion in a queue using pointers

Bubble sort, In this sorting algorithm, multiple swapping occurs in one pas...

In this sorting algorithm, multiple swapping occurs in one pass. Smaller elements move or 'bubble' up to the top of the list, so the name given to the algorithm. In this method,

SORTING ALGORIthm, the deference between insertion,selection and bubble sor...

the deference between insertion,selection and bubble sort

Postfix expression, Ask question Write an algorithm for the evaluation of a...

Ask question Write an algorithm for the evaluation of a postfix expression using a stack#Minimum 100 words accepted#

Storing street addresses with doubly linked lists, Write a C++ program with...

Write a C++ program with header and source les to store street addresses using the Doubly Linked List ADT. Modify the Node class from Lab Assignment 3 so that it becomes a node in

Undirected graph and adjacency matrix, Q. Consider the specification writte...

Q. Consider the specification written below of a graph G V(G ) = {1,2,3,4} E(G ) = {(1,2), (1,3), (3,3), (3,4), (4,1)} (i)        Draw the undirected graph. (

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

Type of qualitative method, Type of Qualitative Method: Different  qua...

Type of Qualitative Method: Different  qualitative methods are suitable for different  types of study. Quite often we can  combine  qualitative and quantitative  methods. Many

Efficient way of storing a sparse matrix in memory, Explain an efficient wa...

Explain an efficient way of storing a sparse matrix in memory.   A matrix in which number of zero entries are much higher than the number of non zero entries is called sparse mat

Simulation of queues, Simulation is the process of making an abstract model...

Simulation is the process of making an abstract model of a real world situation in order to be aware of the effect of modifications and alterations and the effect of introducing nu

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