'15-'16 Text Compression


#1

Use this as a space to record your feedback and questions about this lesson.


#2

I used aaaaaaaaaaaaaaaa for the Aaaaa… pattern. I got 25 bytes total and and 90.47 % compression.
Lots of great ideas and teachable bits (excuse the pun) come out of this one !.


#3

I enjoyed the doing the lesson as much as Robert. But I wasn’t as successful as Robert. I can’t wait do this lesson with my students.


#4

The lessons are a continuation of how to encode messages, in this case not only text messages but also images, and as the files growth bigger, the need to use compression techniques in order to decrease the file size. I will follow the lessons outline, use the resources provided, and the rubric provided for assessment.


#5

Looked for repeating patterns and watched as they were removed from the original text. I was able to get about 45% compression. Plan to follow the lesson with activities.


#6

I looked for repeating patterns when I started. I didn’t realize that I could use pattern of symbols to compress even further until I tried to beat someone else’s compression percentage.


#7

I got 29% compression. I replaced the similar phrase with a symbol. My heuristic is trial and error.


#8

Rules for heuristic

  1. Look at words that repeat more than once.
  2. See if you get a positive compression.
  3. Look to see if there are phrases that repeat for compression.
  4. Compare the before and after results to see if there is any improvement,

I used the ‘Old Woman’ poem; and I got a compression rate of 17.49%. There might have been a bigger compression rate, but it would have been at a loss of the integrity of the poem. It might have gotten so confusing, that the wrong graphics might have been placed in the wrong slots.


#9

I loved this lesson. Probably because I love to play and enjoy a challenge. I remember doing this during our PD and having fun trying to beat others around us. I’m sure my students will love it as well. I looked for repeating patterns and tried several ways to see which gave me the best compression. Using Pitter Patter I achieved a compression rate just over 39%. Using Aaaaa my best compression rate was somewhere around 88%.


#10

This was great lesson to teach compression of files. The tool was great! Tried the letter a too and get gave negative compression. I need remember the dictionary is also part of file size. Great Lesson!


#11

I looked for repeated characters (sequential) in the ascii text that may or may not have been whole words and entered them into my dictionary. Started with the longest strings that I could and worked my way down.

Then I looked for repeated characters with the symbols and entered them into the dictionary. I repeated this process until I could not see any repetition left.

Out of all of the poems I was able to compress the final one the most. I did not write down the percentage but it was in the high 80’s.


#12

I did sea shells. I looked for repeated phrases, then repeated words, then repeated strings of symbols. I got 34.27%.


#13

I did the She sells sea shells by the sea shore and got 26.4% compression. The trial and error led to the conclusion that larger words or repeated phrases brought higher compression rates than using one or two letters and space. Using that process, I got nearly 90%compression on Aaaaa… pattern. I am sure that the students will definitely have a ball trying to beat each other’s scores.


#14

It is so good to see that if you compression on highly repetitive words then it gives better compression. Loved the way we can use compression on already compressed word as well.


#15

It worked for me earlier and then it is not working for me now.


#16

I was able to get 27.57% on the Sea Shore one. The trick is to compress the characters. This was fun and engaging.


#17

This was a lesson my partner and I introduced. It was fun and simple but also required formalized thought to identify the patterns needed for best compressions. Again, students are required to develop a formalized method of problem solving for optimal results.


#18

I did the old lady who swallowed. The best my compression was 24.33%
My Heuristic was to find a word which was at least three letters long and include the space after which repeated at least twice and replace with a symbol. I then looked for prefix or suffixes which also repeated at least twice and were 3 letters long and included the space either before or after.


#19

I did the old lady who swallowed a fly. Like others i looked for repeated patterns and watched the compression value. Ultimately I got a 25.86% compression with the following mapping:
_swallowed
the
iggled
_bird
spider
_she
_catch
_and
_fly

I took the whole poem and was able to get a 75.29% compression and there are still probably things I missed.


#20

Rules:
Look for common letters grouped together and represent them with a character.
Group same letters together such as aaaaaaa to represent a character
Check your compression as you make changes.
Use a character/symbol to represent a characters/symbols when needed.