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Tuesday, February 17, 2015

Huffman Coding Algorithm With Example

Huffman coding algorithm was invented by David Huffman in 1952. It is an algorithm which works with integer length codes. A Huffman tree represents Huffman codes for the character that might appear in a text file. Unlike to ASCII or Unicode, Huffman code uses different number of bits to encode letters. If the number of occurrence of any character is more, we use fewer numbers of bits. Huffman coding is a method for the construction of minimum redundancy codes.

Also Read: Kruskal’s Algorithm for Finding Minimum Cost Spanning Tree

Huffman tree can be achieved by using compression technique. Data compression have lot of advantages such as it minimizes cost, time, bandwidth, storage space for transmitting data from one place to another.

In regular text file each character would take up 1 byte (8 bits) i.e. there are 16 characters (including white spaces and punctuations) which normally take up 16 bytes. In the ASCII code there are 256 characters and this leads to the use of 8 bits to represent each character but in any test file we do not have use all 256 characters. For example, in any English language text, generally the character ‘e’ appears more than the character ‘z’. To achieve compression, we can often use a shorter bit string to represent more frequently occurring characters. We do not have to represent all 256 characters, unless they all appear in the document. The data encoding schemes broadly categorized in two categories.

Fixed Length Encoding Scheme

Fixed length encoding scheme compresses our data by packing it into the minimum number of bits i.e. needed to represent all possible values of our data. The fixed length code can store maximum 224,000 bits data.

Variable Length Encoding Scheme

In variable length encoding scheme we map source symbol to variable number of bits. It allows source to be compressed and decompressed with zero error.

Construction of Huffman Code

A greedy algorithm constructs an optimal prefix code called Huffman code. The algorithm builds the tree T corresponding to the optimal code in a bottom-up manner. It begins with a set of |C| leaves (C is the number of characters) and perform |C| - 1 ‘merging’ operations to create the final tree. In the Huffman algorithm ‘n’ denotes the number of set of characters, z denotes the parent node and x & y are the left & right child of z respectively.

Also Read: Dijkstra Algorithm for Finding Shortest Path of a Graph

Huffman (C)

1. n=|C|

2. Q=C

3. for i=1 to n-1

4. do

5. z=allocate_Node()

6. x=left[z]=Extract_Min(Q)

7. y=right[z]=Extract_Min(Q)

8. f[z]=f[x]+f[y]

9. Insert(Q,z)

10. return Extract_Min(Q)

Analysis

The Q is initialized as a priority queue with the character C.

Q=C can be performed by using Build_Heap in O(n) time.

For loop takes (|n|-1) times because each heap operation requires O(log n) time.

Hence the total running time of Huffman code on the set of n characters is O(n log n).

Method

The following general procedure is applied for construction a Huffman tree:

Search for the two nodes having the lowest frequency, which are not yet assigned to a parent node.

Couple these nodes together to a new interior node.

Add both the frequencies and assign this value to the new interior node.

The procedure has to be repeated until all nodes are combined together in a root node.

Huffman Coding Example

Construct a Huffman tree by using these nodes.

Value	A	B	C	D	E	F
Frequency	5	25	7	15	4	12

Solution:

Step 1: According to the Huffman coding we arrange all the elements (values) in ascending order of the frequencies.

Value	E	A	C	F	D	B
Frequency	4	5	7	12	15	25

Step 2: Insert first two elements which have smaller frequency.

Value	C	EA	F	D	B
Frequency	7	9	12	15	25

Step 3: Taking next smaller number and insert it at correct place.

Value	F	D	CEA	B
Frequency	12	15	16	25

Step 4: Next elements are F and D so we construct another subtree for F and D.

Value	CEA	B	FD
Frequency	16	25	27

Step 5: Taking next value having smaller frequency then add it with CEA and insert it at correct place.

Value	FD	CEAB
Frequency	27	41

Step 6: We have only two values hence we can combined by adding them.

Huffman Tree

Value	FDCEAB
Frequency	68

Now the list contains only one element i.e. FDCEAB having frequency 68 and this element (value) becomes the root of the Huffman tree.

If you find anything missing or incorrect in above tutorial then please mention it by commenting below.

Cascading parameters example in Pentaho CDE

Hi Guys,

It is quite easy to learn about cascading parameters in pentaho CDE dash boarding.

Example below teach you how to give cascading parameters on CDE dashboard.

Environment :
C-Tools 13.09
Pentaho BA Server 4.8 stableb
DB : postgreSQL foodmart ( jasperservers database)

IDEA of cascading parameters:

Example:

1) Lay out section

* Design your lay out for keeping the parameters on dasbharod.

* Sample reference design of layout.

2) Components section

* You need to define 3 selects for 3 parameters

* You need to define 3 parameters

* Observer the Sample worked out image below

* Define 2 parameters for country and state(paramCountry and paramState)

* Define 3 Selects for displaying the selection of parameters on dashboard.

( CountrySelectComponent, StateSelectComponent, CitySelectComponent)

Parameters

1. ParamCountry

i.e, Name= paramCountry and Propertyvalue=USA(default value)

2. paramState

Name=paramState and Propertyvalue=OR(default value)

NOTE : you need NOT to create parameter for city in this case.

Select Components

* Select components are used to display the data coming from sequel query on dashboard as drop down list at the respected place holders.

1) CountrySelectComponent

Name: CountrySelecte Component

Parameter: paramCouentry (you should give param name otherwise, it wont work)

Datasource: give the query name (will discussion in Datasource selection)

HtmlObject : countrySelect

2)StateSelectComponent

Name: StateSelectComponent

Parameter : paramState

Listners : paramCountry

Parameters : Arg(paramCountry) and val(paramCountryP)

Datasource : queryState

HtmlObject : stateSelect

3) CitySelectComponent

* You need add two listners and two parameters at Listerns and parameters properties

Name;CitySelectComponent

Parameter : No need to give any parameters name here as we are not using parameter for city sleelct

Listners : paramState,paramCountry

Parameters :

Arg(paramCountry) and val(paramCountry)

Arg(paramState) and val(paramState)

Datasource : queryCity

HtmlObject : citySelect

3) Data Sources section:

Write queries for 3 selects

1) queryCountry(above image)

Name: queryCountry

Driver: org.postgresql.Driver

User name : postgres

Password : postgres

URL : jdbc:postgresql://localhost:6062/foodmart (5432 is the default port number for postgreSQL)

Query: SELECT DISTINCT country from customer

Parameters : paramCountry(arg) and paramCountry(val)

2) queryState(image is not shown in post refere queryCountry image)

Name: queryState

Driver: org.postgresql.Driver

User name : postgres

Password : postgres

URL : jdbc:postgresql://localhost:6062/foodmart (5432 is the default port number for postgreSQL)

Query: SELECT DISTINCT state_province from customer where country=${paramCountry}

Parameters : paramCountry(arg) and paramCountry(val)

3) queryCity(image is not shown in post refere queryCountry image)

Name: queryCity

Driver: org.postgresql.Driver

User name : postgres

Password : postgres

URL : jdbc:postgresql://localhost:6062/foodmart (5432 is the default port number for postgreSQL)

Query: SELECT DISTINCT city from customer WHERE country=${paramCountry} AND state_province=${paramState}

Parameters : paramCountry(arg) and paramCountry(val)

paramState(arg) and paramState(val)

Save the dashboard and see the preview.

Final output:

1) Test 1

2) Test2

Thank you for reading this post :) :)

for queries and suggestions : sadakar.1988@gmail.com

SOURCE CODE OF THIS EXAMPLE:

https://drive.google.com/file/d/0BymV_QP4TGBEZGhpb1hySDBoSEE/edit?usp=sharing

:-)

PhoneGap creating forms and validating forms example using jquerymobile

Hi friends,

I am going to explain you how to create forms and validate them according to input.

Title: Creating forms using jquerymobile and validating them and sending request to server and getting some response from server.

Here is the project structure :

colors.css

label
.missing

{

color:#FF0000;

font-weight:bold;

}

wait.gif

Add the following image

index.html

DOCTYPE html>

html>

<head>

<title>New Claim</title>

// Global declarations - assignments made in $(document).ready() below

var hdrMainvar = null;

var contentMainVar = null;

var ftrMainVar = null;

var contentTransitionVar = null;

var stateLabelVar = null;

var whatLabelVar = null;

var stateVar = null;

var whatVar = null;

var form1var = null;

var confirmationVar = null;

var contentDialogVar = null;

var hdrConfirmationVar = null;

var contentConfirmationVar = null;

var ftrConfirmationVar = null;

var inputMapVar = null;

// Constants

var MISSING = "missing";

var EMPTY = "";

var NO_STATE = "ZZ";

</script>

head>

body>

div data-role="page" data-theme="a" id="page1">

<h1>Simple Registration</h1>

</div>

<label for="title">Title*</label>

</div>

<label for="fname" id="fnameLabel" name="fnameLabel">First name*</label>

</div>

</div>

<label for="email">Email*</label>

</div>

<label for="phone">Phone</label>

</div>

<label for="street">Street address*</label>

</div>

</div>

<label id="stateLabel" for="state">State*</label>

<option value="ZZ">Please select a state</option>

<option value="AL">Alabama</option>

<option value="AK">Alaska</option>

<option value="AZ">Arizona</option>

<option value="AR">Arkansas</option>

<option value="CA">California</option>

<option value="CO">Colorado</option>

<option value="CT">Connecticut</option>

<option value="DE">Delaware</option>

<option value="FL">Florida</option>

<option value="GA">Georgia</option>

<option value="HI">Hawaii</option>

<option value="ID">Idaho</option>

<option value="IL">Illinois</option>

<option value="IN">Indiana</option>

<option value="KS">Kansas</option>

<option value="KY">Kentucky</option>

<option value="LA">Louisiana</option>

<option value="ME">Maine</option>

<option value="MD">Maryland</option>

<option value="MA">Massachusetts</option>

<option value="MI">Michigan</option>

<option value="MN">Minnesota</option>

<option value="MS">Mississippi</option>

<option value="MO">Missouri</option>

<option value="MT">Montana</option>

<option value="NE">Nebraska</option>

<option value="NV">Nevada</option>

<option value="NH">New Hampshire</option>

<option value="NJ">New Jersey</option>

<option value="NM">New Mexico</option>

<option value="NC">North Carolina</option>

<option value="ND">North Dakota</option>

<option value="OK">Oklahoma</option>

<option value="OR">Oregon</option>

<option value="PA">Pennsylvania</option>

<option value="RI">Rhode Island</option>

<option value="SC">South Carolina</option>

<option value="SD">South Dakota</option>

<option value="TN">Tennessee</option>

<option value="TX">Texas</option>

<option value="VT">Vermont</option>

<option value="VA">Virginia</option>

<option value="WA">Washington</option>

<option value="WV">West Virginia</option>

<option value="WI">Wisconsin</option>

<option value="WY">Wyoming</option>

</select>

</div>

<label for="zip">Postal code*</label>

</div>

<label id="whatLabel" for="what">Please explain what happened*:</label>

</div>

</div>

</form>

</div>

<div>Please fill in all required fields before submitting the form.</div>

</div>

<div align="CENTER"><h4>Your claim has been sent. Please wait.</h4></div>

</div>

<h1>Claim Created</h1>

</div>

<p>A new claim has been created based on data you have submitted.</p>

<p>Your confirmation number is: <span id="confirmation" name="confirmation"></span> </p>

</div>

$(document).ready(

function() {

// Assign global variables

hdrMainVar = $(

#hdrMain);

contentMainVar = $(

#contentMain);

ftrMainVar = $(

#ftrMain);

contentTransitionVar = $(

#contentTransition);

stateLabelVar = $(

#stateLabel);

whatLabelVar = $(

#whatLabel);

stateVar = $(

#state);

whatVar = $(

#what);

form1Var = $(

#form1);

confirmationVar = $(

#confirmation);

contentDialogVar = $(

#contentDialog);

hdrConfirmationVar = $(

#hdrConfirmation);

contentConfirmationVar = $(

#contentConfirmation);

ftrConfirmationVar = $(

#ftrConfirmation);

inputMapVar = $(

input[name*="_r"]);

hideContentDialog();

hideContentTransition();

hideConfirmation();

});

#buttonOK).click(function() {

hideContentDialog();

showMain();

return false;

});

#form1).submit(function() {

var err = false;

// Hide the Main content

hideMain();

// Reset the previously highlighted form elements

stateLabelVar.removeClass(MISSING);

whatLabelVar.removeClass(MISSING);

inputMapVar.each(

function(index){

this).prev().removeClass(MISSING);

});

// Perform form validation

inputMapVar.each(

function(index){

if($(this).val()==null || $(this).val()==EMPTY){

this).prev().addClass(MISSING);

err =

true;

}

});

if(stateVar.val()==NO_STATE){

stateLabelVar.addClass(MISSING);

err =

true;

}

if(whatVar.val()==null||whatVar.val()==EMPTY){

whatLabelVar.addClass(MISSING);

err =

true;

}

// If validation fails, show Dialog content

if(err == true){

showContentDialog();

return false;

}

// If validation passes, show Transition content

showContentTransition();

// Submit the form

$.post(

"requestProcessor.php", form1Var.serialize(), function(data){

confirmationVar.text(data);

hideContentTransition();

showConfirmation();

});

return false;

});

function hideMain(){

hdrMainVar.hide();

contentMainVar.hide();

ftrMainVar.hide();

}

function showMain(){

hdrMainVar.show();

contentMainVar.show();

ftrMainVar.show();

}

function hideContentTransition(){

contentTransitionVar.hide();

}

function showContentTransition(){

contentTransitionVar.show();

}

function hideContentDialog(){

contentDialogVar.hide();

}

function showContentDialog(){

contentDialogVar.show();

}

function hideConfirmation(){

hdrConfirmationVar.hide();

contentConfirmationVar.hide();

ftrConfirmationVar.hide();

}

function showConfirmation(){

hdrConfirmationVar.show();

contentConfirmationVar.show();

ftrConfirmationVar.show();

}

</script>

div>

body>

html>

OutPut

Teachers

Tuesday, February 17, 2015

Huffman Coding Algorithm With Example

Fixed Length Encoding Scheme

Variable Length Encoding Scheme

Construction of Huffman Code

Analysis

Method

Huffman Coding Example

Saturday, February 14, 2015

Cascading parameters example in Pentaho CDE

Thursday, February 5, 2015

PhoneGap creating forms and validating forms example using jquerymobile