HOW TO COMPRESS A BOOK?

If text is compressed, it can be easily stored, transmitted, and manipulated. The number 0.00000094 can be compressed as 9.4*10^7 or 9.4E-7. How to compress a piece of text?

To study compression, let us take an example. In English language, we write everything with 26 alphabets, some punctuation and spaces. In computer everything is represented by 0 and 1 called bits.
We can code A as 0001, B as 0010, C as 0011 and so on. But that is not elegant space saving and time saving method. Hence, we will adopt the coding devised by 'Huffman'.

Suppose the following is our message.
BCAADDDCCACACAC
1. LET US CALCULATE THE FREQUENCY OF EACH CHARACTER
B=1; C=6; A=5, D=3
2. SORT THE CHARACTERS IN INCREASING ORDER OF THE FREQUENCY.

B = 1, D = 3, A = 5, C = 6

3. We are going to create tree. First create an empty node. Assign lowest frequency character as left child of the node and next lowest frequency letter as right child of the node. Total the two frequencies and put it in the empty node.

4. Insert another top node into the tree. Here, one child is empty. Insert the next lower frequency in that space. Again, total the frequencies. Put it in the node.

5. Repeat the step for remaining letter C. Then, Assign 0 to the left edge and 1 to the right edge.

    To find the code for any character travel from top; collect the bits, till you reach the character.
  Character         code
       C                      0
       D                   101
      B                     100
      A                      11

    This is the brief, and minimum code to stand for our string.  High frequency characters get shorter codes.  Rarer character gets longer code.
     To decode the bits, we must travel from bottom to the top through the tree.  This is the one of the many methods available to compress the text.  Once that is encoded in bits, volumes of books can be put in thumb nail sized silicon chips.

Comments

THE EARTH, A SUPER ORGANISM

JOIN MY COURSE: "Become a programmer in a day with python" A man called 'love lock' (what a name) proposed a theory called Gaia theory, named after Greek Goddess. It says, "Earth is a self-regulating organism like a human being. The organic life in it interacts with in-organic matter and maintains atmosphere, temperature and environment". Hence the earth is still suitable for the life to thrive. Imagine, in a particular place, there are lot of flowers. Some flowers are white and some are darkly coloured. We know, white reflects light and heat while dark absorbs the same. White flowers can thrive in hot climate. But dark flowers requires cold climate. The absorption and reflection balances and the environment reaches average, warm temperature at which both the flowers can co-exist. This is the essence of "Gaia" theory. On our earth, ...

THE PARABOLA

A jet of water shooting from a hose pipe will follow a parabolic path. What is the so special about parabola. Y= x^2 Draw a graph for the above equation. It will result in a parabola. This parabola is also called unit parabola. Any equation involving square will yield a parabola. Example: Y = 2x^2 +3x+3 (also called quadratic equation) X= 2 and -2, both satisfies the equation 4 = X^2. Parabolic equations always have two solutions. Any motion taking place freely under gravity follows parabolic path. Examples: An object dropped from a moving train, A bomb dropped from flying plane, A ball kicked upwards. If a beam of light rays fall on the parabolic shaped mirror, they will be reflected and brought to focus on a point. This fact is made use of in Dish Antenna, Telescope mirrors, etc. ...

DISORDER IS THE "ORDER OF THE DAY"

Imagine a balloon full of air. The air molecules are moving randomly inside the balloon. Let us pierce the balloon with a pin. The air rushes out. Why should not the air molecules stay inside the balloon safely and ignore the little hole? That is not the way the world works. The molecules always "want to occupy as many states as possible". Hence the air goes out in the open to occupy more volume. The things always goes into disorder (entropy) and the disorder increases with time. The above statement is what we call "second law of thermodynamics". Consider a cup of coffee on the table. Suppose the heat from entire room flows to your cup of coffee, the coffee will boil and the rest of the room will freeze. Freezing means bringing things to order and arrangement. It violates the second law. Hence it will never happen. Hence heat must flow from high ...

sciencecapsules

Search This Blog