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

Tree traversal, Q. What do you understand by the tree traversal? Write down...

Q. What do you understand by the tree traversal? Write down the procedure for traversing a binary tree in preorder and execute it on the following tree.    Ans: Th

Notes, Ask question #Minimum 10000 words accepted#

Ask question #Minimum 10000 words accepted#

Write a procedure that produces independent stack, Write a procedure (make-...

Write a procedure (make-stack) that produces independent stack objects, using a message-passing style, e.g. (define stack1 (make-stack))  (define stack2 (make-stack)) W

Hashing, explain collision resloving techniques in hasing

explain collision resloving techniques in hasing

Array, extra key inserted at end of array is called

extra key inserted at end of array is called

Make adjacency matrix for un-directed graph, Q. Describe the adjacency matr...

Q. Describe the adjacency matrix and make the same for the given undirected graph.    Ans: The representation of Adjacency Matrix: This representation consists of

Applications of linear and binary search, The searching method are applicab...

The searching method are applicable to a number of places in current's world, may it be Internet, search engines, text pattern matching, on line enquiry, finding a record from data

Example of binary search, Let us assume a file of 5 records that means n = ...

Let us assume a file of 5 records that means n = 5 And k is a sorted array of keys of those 5 records. Let key = 55, low = 0, high = 4 Iteration 1: mid = (0+4)/2 = 2

Depth of complete binary tree, What will be depth do , of complete binary t...

What will be depth do , of complete binary tree of n nodes, where nodes are labelled from 1 to n with root as node and last leaf node as node n

Explain time complexity, Time Complexity, Big O notation The amount of ...

Time Complexity, Big O notation The amount of time needed by an algorithm to run to its completion is referred as time complexity. The asymptotic running time of an algorithm i

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