January 22nd Run length Encoding Co:mpression

Today we are going to complete some exercises on  Run Length Encoding (RLE)


Homework   AJT

By next lesson RESEARCH and make a CAESER cipher.


Task 1

In your books or in your Google doc write a definition of RLE.  Include the source

Task 2

Use the Run Length Encoding Calculator to encode these text strings.
Text string	Answer
AAAABBBBBBBBBCADDDDEEFFFFFFFF
ABCABCABCABCABCABCABCABCABCS
BBGGYYAACCFFEEBBGGYYAACCFFEE
Which one compresses the most?
Why is this?
Describe in English the process the RLE calculator follows to encode a piece of text.

Task 3

An RLE compression algorithm works by removing repeated data and replacing it with a number representing the run length of that item.

·         Fill in the gaps to complete this algorithm.

1. Start with the first character in the string.

2. Write down the number 1.

3. Compare the first character with the next character on the right.

4. If they are the same, ___________________________________.

5. If they are not the same, ________________________________.

6. Move on to the next character on the right.

7. Go back to step 2 and repeat until you reach the end of the string.

8. _____________________________________________________.

Task 4

        Test out the algorithm using these data strings:

o   AAAABBBBBBBBBCADDDDEEFFFFFFFF

o   ABCABCABCABCABCABCABCABCABCS

o   BBGGYYAACCFFEEBBGGYYAACCFFEE