Tuesday, 23 November 2021

Sequence DataType Part - II [Indexing]

Sequence data operations: Indexing

Indexing just means accessing elements. To access elements, the square brackets can be used. There 
are many methods to access elements in python.

index() method finds the first occurrence of the specified value and returns its position 

Syntax: object.index(sub[, start[, end]] ), object[index]

•   Index of the element is used to access an element from ordered sequences
•   The index starts from 0
•   Negative indexing is used to access elements from the end of a list
•   In negative indexing, the last element of a list has the index -1

String Indexing

The first let us look at what string data type is. A string is a sequence of one or more characters, for example, it can contain letters, numbers and symbols and that can be either a constant or variable. And strings are basically a mutable sequence in Python. So, to create a string we can close a sequence of characters inside single, double or triple quotes. Let us see an example on creating string. Create string includes A sequence of characters inside single, double or triple quotes. I am creating the string called strsample and it has a sequence of characters which describes the word learning and storing that on two variable called strsample. So that becomes a string. So we can print out strings by simply calling the print function. So when we print the string strsample will be getting an output call learning. So the strsample is now a string.





List Indexing

So let us move to the next sequence data that is called list.So here I am just going to illustrate you the indexing part using the list sequenced data. So syntax
is given here you can use the list name and you can use the index function. And inside the
function we can just give the element for which you want to find the position. So I have already
created a list call list lstsample which has few elements to it. It has both numbers and strings and
to find the index of the element sam I can use the index method.

Inside the method I can just give the element sam. So that gives me an output three because
index corresponds to Sam is 3. The index corresponds to 1 is 0 and the index corresponds 2 is 1

and index corresponds to a is 2 and index corresponds to sam is 3. But if you are going to find
the element corresponding to a given index, then you can get that using square brackets. So let us
just try that I am using lissample of two inside the square bracket.

So it is going to give me an element which response to the index 2 which is nothing but a here.
Similarly you can access any elements from the end of a list as well using the negative indexing.
So if I give lissample of -1 is going to give me the last element of the list lissample. So which is
nothing but 2.







Array Indexing 

Similarly we can perform the indexing on an array. So we have already seen how to create an
array. So let us just use the same example. So I print out the values of array. The array sample
has values 1, 2, 3 and 4. So, here I just have an example to show you how you can perform the
negative index on this array. I am accessing the third last element of the array so it is going to
give me the value 2 which is nothing but the third last element of the array.

And similarly we can perform that on a tuple. So you can use the index method to find the
position of the given elements. So let me just use py so the index of py is 5. So here I am just
trying to find the element which responds to the second index which is 3 here. So, let us see how
the indexing works in set.


So we were already created a set sample which has example 24, 87.5 data 24 and data as
element to it. I am trying to use an index call 4 which gives me an error saying set object is not
subscriptable which means that you cannot perform the indexing operation set. As we know that
set is container to hold non sequential data. You will not be able to access the elements inside the
set using indexing.




Dictionary Indexing

So next we are going to see how we can perform indexing on a dictionary. So, Python dictionary
object provides a key-value pair facility. So the values in the dictionary are indexed by keys and
they are not held in any order. So, if you want to access the values from the dictionary then you
can access them by using their keys. So we have dictionary called dict sample which we have
already created which has keys as one second 3 and 4 and it also has a key value corresponding
to it.

For example first, 2, 3 and 4 so now let us see what happens when you are trying to access an
element using a index I am using index say for example that is 2 it gives you the key error that is
2 as we know that values in a dictionary or indexed by keys. So you will be able to access them
using keys not using the index. So now I am using key inside my square braces. So I am going to
get a value corresponding to the key that is 1.

So the value corresponding to the key one is first and as we know that he can may be a string or
integer value. So key can either have string as well as a integer. So here I have a key called
second so I will be able to access the value corresponding to the key second. So I am getting
output as 2. So, the value corresponding to key second is 2.







Range Indexing



So the last one example which is the last one is to illustrate the indexing using range. So we have
already created range sample which contains a value is 1, 5 and 9. So, you should be using an
appropriate value which is already there in your range if you are trying to give you a value which
is not in the range then it is going to throw you a value error. We are trying to check the index
corresponding to the value zero.

But in our case the range sample does not have the value 0 at all because it has only the values 1,
5, 9 in that case it throws a value error. So it says zero is not in range. But if you are trying to
find the position of the given element that is 9 here you will be able to do that because we
already have a range value that is 9 and it gives you the position of that particular element that is
2 and we can also get the elements given the index.

So, given the index as one, so it give the output as 5 because the index corresponding to the
value one is zero and the index corresponding to the value 5 is 1. But if you are trying to give the
index which is out of range then it is also going to throw you an error saying index error because
you have an error in the given index that is why the error says it is index error and saying range

object index out of range. Because you do not have any element corresponding to the index 9
that is, why the error says index error.






















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Monday, 22 November 2021

Sequence DataType Part - I

Sequence data type


•   Strings - Sequence of characters - " (or) '




•   Tuples - Sequence of compound data - ()




•   Lists - Sequence of multi-data type objects - []




•   Arrays - Sequence of constrained list of objects (all objects of same datatype) using array module from array package




•   Dictionary- Sequence of key-value pairs - {}




•   Sets - Sequence of unordered collection of unique data





•   Range - Used for looping - using built-in range( )










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Sunday, 21 November 2021

Introduction to java | Java tutorials | History of Java | JDK | JVM | JRE | Different Types of Java Platforms

What is Java?

Java is a class-based object-oriented programming language.

It is the most popular programming language.

Building web and desktop applications.

The language of choice for Android programming.

 

Java Platform

Java Platform is a collection of programs that help programmers to develop and run Java programming applications efficiently.

It includes an execution engine, a compiler, and a set of libraries in it.

It is a set of computer software and specifications.

James Gosling developed the Java platform at Sun Microsystems, and the Oracle Corporation later acquired it.

Java is a multi-platform, object-oriented, and network-centric language. It is among the most used programming language. Java is also used as a computing platform.

What is Java used for?

It is used for developing Android Apps

Helps you to create Enterprise Software

Wide range of Mobile java Applications

Use for big data Analytics.

Java Programming of Hardware devices

Used for Server-Side Technologies like Apache, JBoss, GlassFish, etc.

 

History of Java Programming Language

The Java language was initially called OAK.

it was developed for handling portable devices and set-top boxes.

In 1995, Sun changed the name to “Java” and modified the language to take advantage of the burgeoning www (World Wide Web) development business.

Later, in 2009, Oracle Corporation acquired Sun Microsystems and took ownership of three key Sun software assets: Java, MySQL, and Solaris.

Java Versions

JDK Alpha and Beta

   1995

JDK 1.0

23rd Jan 1996

JAVA SE 15

           15th Sep 2020 (latest Java Version)

 

 

Java Features

  • It is one of the easy-to-use programming languages to learn.
  • Write code once and run it on almost any computing platform.
  • Java is platform-independent. Some programs developed in one machine can be executed in another machine.
  • It is designed for building object-oriented applications.
  • It is a multi threaded language with automatic memory management.
  • It is created for the distributed environment of the Internet.
  • Facilitates distributed computing as its network-centric.

Java Development kit (JDK)

 

JDK is a software development environment used for making applets and Java applications.

Java developers can use it on Windows, macOS, Solaris, and Linux.

It is possible to install more than one JDK version on the same computer.

Why use JDK?

 

· JDK contains tools required to write Java programs and JRE to execute them.

· It includes a compiler, Java application launcher, Applet viewer, etc.

· Compiler converts code written in Java into byte code.

Java Virtual Machine (JVM):

 

Java Virtual Machine (JVM) is an engine that provides a runtime environment to drive the Java Code or applications.

It converts Java bytecode into machine language.

Why use JVM?

  • JVM provides a platform-independent way of executing Java source code.
  • It has numerous libraries, tools, and frameworks.
  • Once you run a Java program, you can run on any platform and save lots of time.
  • JVM comes with JIT (Just-in-Time) compiler that converts Java source code into low-level machine language. Hence, it runs faster than a regular application.

Java Runtime Environment (JRE)

JRE is a piece of software that is designed to run other software.

It contains the class libraries, loader class, and JVM.

If you are not a programmer, you don’t need to install JDK, but just JRE to run Java programs.

Why use JRE (Java Runtime Environment)

  • JRE contains class libraries, JVM, and other supporting files. It does not include any tool for Java development like a debugger, compiler, etc.
  • It uses important package classes like math, swing, util, lang, awt, and runtime libraries.
  • If you have to run Java applets, then JRE must be installed in your system.

 

Different Types of Java Platforms

1.       Java Platform, Standard Edition (Java SE):

Java SE’s API offers the Java programming language’s core functionality.

It defines all the basis of type and object to high-level classes.

It is used for networking, security, database access, graphical user interface (GUI) development, and XML parsing.

 

2.       Java Platform, Enterprise Edition (Java EE):

The Java EE platform offers an API and runtime environment for developing and running highly scalable, large-scale, multi-tiered, reliable, and secure network applications.

 

3.       Java Programming Language Platform, Micro Edition (Java ME):

The Java ME platform offers an API and a small-footprint virtual machine running Java programming language applications on small devices, like mobile phones.

 

API :  Application programming interface

An API is a set of programming code that enables data transmission between one software product and another. It also contains the terms of this data exchange.

 

4.       Java FX: 

JavaFX is a platform for developing rich internet applications using a lightweight user-interface API. It user hardware-accelerated graphics and media engines that help Java take advantage of higher-performance clients and a modern look-and-feel and high-level APIs for connecting to networked data sources.

First Program :

 

Class abc {

Public static void main(String args[]){

System.out.println(“Hello World”);

}

}

 


Types of Operators in Python

Assignment Operator 

Assignment operators are used to assign values to variables.

 There are 5 types of assignments operators 




Relational or Comparison Operator


Relational operator tests numerical equalities and inequalities between two operands and returns a boolean value

All operators have same precedence

So now, we will create two variables x and y with values 5 and 7 respectively and test the operators on them.




       
Logical Operators

Logical Operators are used when operands are conditional statements and it returns boolean value.

In python, logical operators are designed to work with scalars or boolean values.




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Operators in Python


Operators and Operands

Operators are special symbol that help in carrying out an assignment operation or arithmetic or logical computation

Value that the operator operates on is called operand

Example:

2 + 3 = 5 

Here, plus sign ("+") is the Operator and "2","3" are the Operands.

Arithmetic Operators 

Used to perform mathematical operations between two operands.

So now, we will create two variables as a = 10 and b = 5 and perform some basic operations on them.




Hierarchy of arithmetic operators


Example:

Monday, 11 October 2021

Saturday, 9 October 2021

Introduction to Python


Evolution of Python.

 -Python was developed by Guido Van Rossum in the late eighties at the ' National Research Institute       for Mathematics and Computer Science, at Netherlands.

 Python Editions 

  - Python 1.0
  - Python 2.0
  - Python 3.0

Advantages of  using Python

- Python has several features that make it well suited for data science

- Open source and community development 

- Developed under Open Source Intiative approved license making it free to use and      distribute even commercially

- Syntax used is simple to understand and code 

- Libraries designed for specific data science tasks 

- Combines well with majority of the cloud platform service providers

Integrated development enviroment (IDE)

- Software application consisiting of a cohesive unit of tools required for development

- Designed to simplify software development

- Utilities Provided by IDEs include tools for managing, compiling, deploying and debugging software

Feature of IDE 

- IDE should centralize three key tools nthat form the crux of software development 

- Syntax and error highlighting 

-  Code completion 

- Version control

Commonly used IDEs

-Spyder
-PyCharm
-Jupyter Notebook
-Atom

But in this course we are going to be looking at jupyter notebook; and that is primarily because it is a very good software that has been developed only for data science and python; and it as an interface that is very very appealing and easy to use for beginners.

Jupyter Notebook

-Web application that allows creation and manipulation of notebook documents called 'notebook',

-Supported across Linux, Mac Os X and windows platforms.

-Available as open source version.

-Bundled with Anaconda distribution or can be installed seperately.

-Supports Julia, Python, R and Scala.
 
-Consists of ordered collection of input and output cells that contain code,text,plots etc.

-Allows sharing of code and narrative text through output format likePDF,HTML etc.




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Wednesday, 6 October 2021

Control structures [if elif]


Control structures 

if elif

  •    Whenever you want to execute certain commands only when the certain condition is satisfied. 
  •    So, in that case you can go for if else statements, the condition can also be single or you can also give multiple condition, in that case you will have multiple else statements.
  • In the image below you can see this, more clearly.

     



  • So, first we will look into the if else family of constructs, if else and If-elif-else are a family of constructs, where a condition is first checked, if it is satisfied only then the operations will be performed. 
  • If, the condition is not satisfied the code exits the construct or moves on to the other options. So, whenever we use just an if statement or with an else statement or with using multiple if's and multiple else clause. 
  • The first check would be the condition, whenever the condition is satisfied only then the code will be executed or the statement will be executed, otherwise the code exits the construct itself and moves to the other options. So, that is how the if else family of the constructs works. 


  • Let us see different task for each construct. So, first we will look into if construct, the command would be if expression colon and statements in the next line.
  • If is a key word, if the condition is satisfied whatever condition you have given it under the expression, then the statements will get executed. Otherwise, the code exit the construct itself. 
  • Next, we will move ahead and see what is the syntax would be for If-else construct
  • It forms a basis from the if construct, wherever we have given the first statement, using the if keyword and followed by if keyword you have to give the expression to be checked, that is where the condition to be specified.

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