Difference between revisions of "Huffman coding"

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  do
 
  do
   Find the two smallest numbers in the histogram
+
   Find the two active nodest with the lowest count, these are the parents
   Create a new node with the sum of the two and a link to the two
+
   Create a new child node and link it to the two parent nodes, let it contain the sum of the two parents
   Mark the two originals as spent
+
   Mark the two parents as as inactive
  loop until only one node remains
+
  loop until only one active node remains
  
 
We will now have a binary tree structure.
 
We will now have a binary tree structure.

Revision as of 03:09, 25 January 2011

A simple way of reducing the size of a block of data is to replace the most common words with shorter ones that are not already used in the data. It is possible to reconstruct the original data using a dictionary that lists the short words and the longer words they replace.

The problem is to decide which codes to use, David A. Huffman found the optimal way of generating codes that guarantees the shortest possible output.

Count the number of times each word occurs in the data, this will be a histogram

do
 Find the two active nodest with the lowest count, these are the parents
 Create a new child node and link it to the two parent nodes, let it contain the sum of the two parents
 Mark the two parents as as inactive
loop until only one active node remains

We will now have a binary tree structure.