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

Trees, What is AVL Tree? Describe the method of Deletion of a node from and...

What is AVL Tree? Describe the method of Deletion of a node from and AVL Tree ?

Define different types of sparse matrix, Q1. Define a sparse matrix. Explai...

Q1. Define a sparse matrix. Explain different types of sparse matrices? Evaluate the method to calculate address of any element a jk of a matrix stored in memory. Q2. A linear

What is solid modeling, What is Solid modeling Solid modeling is the mo...

What is Solid modeling Solid modeling is the most powerful of the 3-D modeling technique. It provides the user with complete information about the model. Defining an object wit

Importance of object-oriented over java, Importance of Object-Oriented over...

Importance of Object-Oriented over java Java is basically based on OOP notions of classes and objects. Java uses a formal OOP type system that should be obeyed at compile-t

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

Merge sort, #question. merging 4 sorted files containing 50,10,25,15 record...

#question. merging 4 sorted files containing 50,10,25,15 records will take time?

Worst case and average case, Worst Case: For running time, Worst case runn...

Worst Case: For running time, Worst case running time is an upper bound with any input. This guarantees that, irrespective of the type of input, the algorithm will not take any lo

Breadth first traversal, The data structure needed for Breadth First Traver...

The data structure needed for Breadth First Traversal on a graph is Queue

Question, A binary search tree is used to locate the number 43. Which of th...

A binary search tree is used to locate the number 43. Which of the following probe sequences are possible and which are not? Explain. (a) 61 52 14 17 40 43 (b) 2 3 50 40 60 43 (c)

Explain memory allocation strategies, Memory Allocation Strategies If i...

Memory Allocation Strategies If it is not desirable to move blocks of due storage from one area of memory to another, it must be possible to relocate memory blocks that have be

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