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

Tower of hanoi, how do we use 4-discs stack to solve tower of hanoi problem...

how do we use 4-discs stack to solve tower of hanoi problem and write an algorithm to solve it?

What are the properties of colour, Properties of colour Colour descript...

Properties of colour Colour descriptions and specifications generally include three properties: hue; saturation and brightness. Hue associates a colour with some position in th

In-order traversal, Write steps for algorithm for In-order Traversal Th...

Write steps for algorithm for In-order Traversal This process when implemented iteratively also needs a stack and a Boolean to prevent the execution from traversing any portion

What are stored and derived attributes, What are stored and derived attribu...

What are stored and derived attributes?  Stored attributes: The attributes kept in a data base are called stored attributes.  Derived attributes: The attributes that are

Program of implementation of stack using arrays, include int choice, st...

include int choice, stack[10], top, element; void menu(); void push(); void pop(); void showelements(); void main() { choice=element=1; top=0; menu()

Program on radix sort., Write a program that uses the radix sort to sort 10...

Write a program that uses the radix sort to sort 1000 random digits. Print the data before and after the sort. Each sort bucket should be a linked list. At the end of the sort, the

State cmy model, CMY Model  The cyan, magenta, yellow (CMY) colour mode...

CMY Model  The cyan, magenta, yellow (CMY) colour model is a subtractive model based on the colour absorption properties of paints and inks. As such it has become the standard

Algorithm to delete node from binary search tree, Normal 0 fals...

Normal 0 false false false EN-IN X-NONE X-NONE MicrosoftInternetExplorer4

Non Recursive Algorithm to Traverse a Binary Tree, Q. Write down a non recu...

Q. Write down a non recursive algorithm to traverse a binary tree in order.                    Ans: N on - recursive algorithm to traverse a binary tree in inorder is as

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