![Variables are nothingbut reserved memory locations to store values. Thismeans that when you
create a variable you reserve some space in memory.
Based on the data type of a variable, the interpreter allocates memory and decides what can be
stored in the reserved memory. Therefore, by assigning different data types to variables, you can
store integers,decimals or characters in these variables.
Ex:
counter =100 # An integer assignment
miles = 1000.0 # A floatingpoint
name = "John" # Astring
String
In programmingterms, we usually call text a string. When you think of a string as a
collection of letters, the term makes sense.
All the letters, numbers,and symbols in this book could be a string.
For that matter, your name could be a string, and so could your
address.
Creating Strings
In Python,we create a string by putting quotesaroundtext. For example, we could take our
otherwise useless
• "hello"+"world" "helloworld" #
concatenatio
n
• "hello"*3 "hellohellohello" # repetition
• "hello"[0] "h" # indexing
• "hello"[-1] "o" # (from end)
Variable](https://image.slidesharecdn.com/python-191119115426/85/Python-22-320.jpg)
![• "hello"[1:4] "ell" #
slicing
• len("hello") 5 # size
• "hello" < "jello" 1 #
compari
son
• "e" in "hello" 1 #
search
Python Operator
Arithmetic Operator
Operator Meaning
Example
+ Add two operands or unary plus
x + y
+2
- Subtract right operand from the left or unary minus
x - y
-2
* Multiply twooperands x * y
/
Divide left operand by the right one (always results
into float)
x / y
%
Modulus - remainder of the division of left operand by
the right
x % y
(remainder
of x/y)
//
Floor division - division that results into whole
number adjusted to the left in the number line
x // y
** Exponent - left operand raised to the power ofright
x**y (x
to the
power y)](https://image.slidesharecdn.com/python-191119115426/85/Python-23-320.jpg)
![Tuples
A tuple is a sequence of immutable Pythonobjects. Tuples are sequences, just
like lists. The differences between tuples and lists are, the tuples cannot be
changed unlike lists and tuples use parentheses, whereas lists use square
brackets.
Creating a tuple is as simple as putting different comma-separated values.
Optionally you can put these comma-separated values between parentheses
also. For example−
tup1 = ('physics','chemistry', 1997,2000);
tup2 = (1, 2, 3, 4, 5 );
tup3 = "a", "b", "c", "d";
Accessing Values in Tuples:
To access values in tuple, use the squarebrackets for slicing along with the
index or indices to obtain value available at that index. For example−
tup1 = ('physics','chemistry', 1997,2000);
tup2 = (1, 2, 3, 4, 5, 6, 7 );
print "tup1[0]: ",tup1[0]
print "tup2[1:5]: ",tup2[1:5]
When the above code is executed, it produces the following result −
tup1[0]: physics
tup2[1:5]: [2, 3, 4, 5]
Basic TuplesOperations
Tuples respond to the + and * operators much like strings; they mean
concatenation and repetition here too, except that the result is a new tuple,
not a string. In fact, tuples respond to all of the general sequence operations
we used on strings in the prior chapter −
Chapter-: 4](https://image.slidesharecdn.com/python-191119115426/85/Python-25-320.jpg)
![The list is a mostversatile datatype available in Pythonwhichcan be written as
a list of comma-separated values (items) between square brackets. Important
thing about a list is that items in a list need not be of the same type.
Creating a list is as simple as putting different comma-separated values
between square brackets.For example −
list1 = ['physics','chemistry', 1997, 2000];
list2 = [1, 2, 3, 4, 5 ];
list3 = ["a", "b", "c", "d"];
Similar to string indices, list indices start at 0, and lists can be sliced,
concatenated and soon.
Accessing Values in Lists:
To access values in lists, use the squarebrackets for slicing along with the index
or indices to obtain value available at that index. For example−
list1 = ['physics','chemistry', 1997, 2000];
list2 = [1, 2, 3, 4, 5, 6, 7 ];
print "list1[0]: ",list1[0]
print "list2[1:5]:", list2[1:5]
Output:list1[0]: physics
list2[1:5]: [2, 3, 4, 5]
Update: list = ['physics', 'chemistry', 1997, 2000];
print "Value available at index 2 :"
print list[2]
list[2] =2001;
print "New value available at index 2 :"
print list[2]
List:](https://image.slidesharecdn.com/python-191119115426/85/Python-27-320.jpg)
![Output:Value available at index 2 :1997
New value available at index 2 :2001
Delete: list1 = ['physics', 'chemistry', 1997,2000];
print list1
del list1[2];
print "After deleting value at index 2 :"
print list1
['physics', 'chemistry', 1997,2000]
Output:After deleting value at index 2 :
['physics', 'chemistry',2000]
Basic ListOperation
Python Expression Results Description
len([1, 2, 3]) 3 Length
[1, 2, 3] + [4, 5, 6] [1, 2, 3, 4, 5, 6] Concatenation
['Hi!'] *4 ['Hi!', 'Hi!', 'Hi!','Hi!'] Repetition
3 in [1, 2, 3] True Membership
for x in [1, 2, 3]: print x, 1 2 3 Iteration
Built-in List Functions & Methods:
SN Function with Description](https://image.slidesharecdn.com/python-191119115426/85/Python-28-320.jpg)
![1 cmp(list1, list2) Compares elements of both lists.
2 len(list) Gives the total length of the list.
3 max(list) Returns item from the list with max value.
4 min(list) Returns item from thelist with min value.
5 list(seq) Converts a tuple into list.
Python includes following list methods
SN Methods withDescription
1 list.append(obj) Appends object obj to list
2 list.count(obj) Returns count of how many times obj occurs in list
3 list.extend(seq) Appends the contents of seq to list
4 list.index(obj) Returns thelowest index in list that objappears
5 list.insert(index, obj) Inserts object obj into list at offsetindex
6 list.pop(obj=list[-1]) Removes and returns last object or obj from list
7 list.remove(obj) Removes object obj from list
8 list.reverse() Reverses objects of list inplace
9 list.sort([func]) Sorts objects of list, use compare func if given
Built-in List Functions & Methods:
SN](https://image.slidesharecdn.com/python-191119115426/85/Python-30-320.jpg)
![nested loops You can use one or more loop inside any another
while, for or do..whileloop.
Example:
For Loop:
>>> for mynum in [1, 2, 3, 4, 5]:
print "Hello",mynum
Hello 1
Hello 2
Hello 3
Hello 4
Hello 5
While Loop:
>>> count =0
>>> while (count <4):
print 'The count is:', count
count = count +1
The count is:0
The count is: 1
The count is: 2
The count is:3](https://image.slidesharecdn.com/python-191119115426/85/Python-32-320.jpg)
![If Statement:
>>> state = “Texas”
>>> if state == “Texas”:
print “TX
TX
If...Else Statement:
>>> if state == “Texas”
print “TX”
else:
print “[inferiorstate]”
If...Else...If Statement:
>>> if name == “Paige”
print “HiPaige!”
elif name == “Walker”:
print “HiWalker!”
else:
print “Imposter!”
Function
Function blocks begin with the keyword def followed by the function name
and parentheses ( ( )).
Any input parameters or arguments should be placed within these
parentheses. You can also define parameters inside these parentheses.
Example:](https://image.slidesharecdn.com/python-191119115426/85/Python-34-320.jpg)
![The first statement of a function can bean optional statement - the
documentation string of the function.
The code block within every function starts with a colon (:) and is indented.
The statement return [expression] exits a function, optionally passing back an
expression to the caller. A return statement with no arguments is the same as
return None.
Syntex:
def functionname( parameters):
"function_docstring"
function_suite
return [expression]
Example:
1. def printme( str ):
"This prints a passed stringinto this function"
print str
return
2. # Function definition ishere
def printme( str ):
"This prints a passed string into this function"
print str
return;
# Now you can call printmefunction
printme("I'm first call to user defined function!")
printme("Again second call to the samefunction")](https://image.slidesharecdn.com/python-191119115426/85/Python-35-320.jpg)
Python
- 1. A Summer Training Report On Python and it’s Libraries Under the Guidance of Mr. K.S. RAJU (Data Scientist) Done By A. K.G (1234567890) At NIT SOFTWARE TRAINIG & DEVELOPMENT Ameerpet, Hyderabad, Telangana 500016 Submitted To Department of Information Technology Rajkiya Engineering College , Bijnor Approved By AICTE, Affiliated to AKTU, LUCKNOW
- 2. Acknowledgement It is our proud privilege and duty to acknowledge the kind of help and guidance received from several people in preparation of this report. It would not have been possible to prepare this report in this form without their valuable help, cooperation and guidance. Firstand foremost, wewish to recordour sincere gratitude to Prof., Mr. Asutosh Mishra for his constant support and encouragement in preparation of this report and for making available library and laboratory facilities needed to prepare this report. The seminar on “Python” was very helpful to us in giving the necessary backgroundinformationand inspiration in choosing this topic for the seminar. Their contributions and technical support in preparing this report are greatly acknowledged. Last but not the least, we wish to thank our parents for financing our studies in this college as well as for constantly encouraging us to learn engineering. Their personal sacrifice in providing this opportunity to learn engineering is gratefully acknowledged.
- 3. Table Of Contents CHAPTER1 . Introduction 1. Python 2. Scripting Language 3. Object Oriented Programming 4. History of python 5. Behind the Scene of Python CHAPTER2 . Downloading & Installing Python 1. Downloading Python 2. Installing Python 3. Setuppath of variable 4. Running The Python IDE 5. Python code Execution. CHAPTER3.Data Types & Operator 1. Variables 2. String 3. Python Operator 4 Arithmetic Operator 5. Comparison Operator 6. Logical Operator
- 4. CHAPTER 4. Tuple & List 1. Tuple 1. Accessing Tuple Values 2. Built in Operation 3. Built in Functions 2. List 1. Accessing List Values 2. Built in Operation 3. Built in Functions CHAPTER5.Loops & Conditional Statements 1. Loops 1. Loops Definition 2. Loops Example 2. Conditional Statement 1. Conditional StatementDefinition 2. Conditional StatementExample 3. Function 1. Syntex & Examples CHAPTER6.Uses & Scope 1. Scope of Python 2. What can we do With Python? 3. Who Uses Python Today? 4. Why do People Use Python
- 5. Introduction of Industry Naresh i Technologies Naresh i Technologies (Pronounced: Naresh) is a leading software training institute providing Software Training, Project Guidance, IT Consulting and Technology Workshops. Using our enhanced global software training delivery methodology, innovative software training approach and industry expertise, we provide high-value corporate training services that enable our clients to enhance business performance, accelerate time-to-market, increase productivity and improve customer service. We serve Global 100 companies and the leading software vendors in Banking & Financial Services, Insurance, Telecommunications, Technology and Media, Information & Education industries. We design and mentor human resources for our clients who create competitive advantage. Founded in 2004 and headquartered in Hyderabad, India, we have offices and training institutes throughout the India. Headquarters – Durga Bhavani Plaza, Ameerpet, Hyderabad. Offices – Hyderabad, Chennai. Training Institutes – Hyderabad, Chennai.
- 6. would be possible in languages such as C++ or Java. The language provides constructs intended to enable clear programs on both a small and large scale. Python supports multiple programming paradigms, including object-oriented, imperative and functional programming or procedural styles Scripting Language A scripting or script language is a programming language that supports scripts, programs written for a special run-time environment that automate the execution of tasks that could alternatively be executed one-by-one by ahuman operator. Scripting languages are often interpreted (rather than compiled). Primitives are usually the elementary tasks or API calls, and the language allows them to be combined into more complex programs A scripting language can be viewed as a domain-specific language for a particular environment; in the case of scripting an application, this is also known as an extension language. Scripting languages arealso sometimes Python Python is a widely used high-level, general-purpose, interpreted, dynamic programming language. Its design philosophy emphasizes code readability, and its syntax allows programmers to express concepts in fewer lines of code than Chapter-:1
- 7. referred to as very high-level programminglanguages, as they operate at a high level of abstraction, or as control languages. Object Oriented Programming Language Object-oriented programming(OOP) is aprogrammingparadigm based on the concept of "objects", which may contain data, in the form of fields, often known as attributes; and code, in the form of procedures, often known as methods. A distinguishing feature of objects is that an object's procedures can access and often modify the data fields of the object with which they are associated (objects have a notion of "this" or "self"). In OO programming, computer programs aredesigned by making them out of objects that interact with one another. There is significant diversity in object- oriented programming, but most popular languages are class-based, meaning that objects are instances of classes, whichtypically also determines their type. History Python was conceived in the late 1980s, and its implementation was started in December 1989 by Guido vanRossum at CWI in the Netherlands as a successor to the ABC language (itself inspired by SETL) capable of exception handling and interfacing with the Amoeba operating system. Van Rossum is Python's principal author, and his continuing central role in deciding the direction of Python is reflected in the title given to him by the Python community, benevolent dictator for life(BDFL).
- 8. “Python is an experiment in how much freedom programmers need. Too much freedom and nobody can read another's code; too little and expressiveness is endangered.” - Guido van Rossum
- 9. Python Releases Python 1.0 - January 1994 Python 1.5 - December 31, 1997 Python 1.6 - September 5, 2000 Python 2.0 - October 16, 2000 Python 2.1 - April 17, 2001 Python 2.2 - December 21, 2001 Python 2.3 - July 29, 2003 Python 2.4 - November 30, 2004 Python 2.5 - September 19, 2006 Python 2.6 - October 1, 2008 Python 2.7 - July 3, 2010 Python 3.0 - December 3, 2008 Python 3.1 - June 27, 2009 Python 3.2 - February 20, 2011 Python 3.3 - September 29, 2012 Python 3.4 - March 16, 2014 Python 3.5 - September 13, 2015 Python 3.6 - December 23, 2016
- 10. About the origin of Python, Van Rossum wrote in 1996: Over six years ago, in December 1989, I was looking for a "hobby" programming project that would keep me occupied during the week around Christmas.My office ...would be closed, but I had a home Computer, and not much else on my hands. I decided to write an interpreter for the new scripting language I had been thinking about lately: a descendant of ABC that would appeal to Unix/C hackers. I chose Python as a working title for the project, being in a slightly irreverent mood (and a big fan of Monty Python's Flying Circus). Behind The Scene of Python
- 11. Why Python ? The language's core philosophy is summarized in the document The Zen of Python (PEP 20), which includes aphorisms such as… Beautiful is better than ugly Simple is better than complex Complex is better than complicated Readability counts Explicit is better than implicit
- 12. If you don’t already have a copy of Pythoninstalled on your computer, you will need to open up your Internet browser and go to the Python download page (http://www.python.org/download/). Now that you are on the download page, select whichof the softwarebuilds you would like to download. For the purposes of this article we will use the most up to date versionavailable(Python3.4.1). Once you have clicked on that, you will be taken to a page witha description of all the new updates and features of 3.4.1, however, you can always read that while the download is in process. Scroll to the bottom of the page till you find the “Download”sectionand click on the link that says “download page.” Chapter-: 2 Downloading Python
- 13. Now you will scroll all the way to the bottom of the page and find the “Windows x86 MSI installer.” If you want to download the 86-64 bit MSI, feel free to do so. We believe that even if you have a 64-bit operating system installed on your computer,the 86-bit MSI is preferable. We say this because it will still run well and sometimes, with the 64-bit architectures, some of the compiled binaries and Python libraries don’twork well. Installing Python
- 14. Once you have downloaded thePython MSI, simply navigate to the downloadlocation on your computer, double clicking the file and pressing Run when the dialog box pops up. If you are the only person whouses yourcomputer,simply leave the “Install for all users” option selected. If you have multiple accounts on your PC and don’twant to install it across all accounts, select the “Install just for me” option then press“Next.” f you want to change the install location, feel free to do so; however,it is best to leave it as is and simply select next,Otherwise...
- 15. Scroll down in the window and find the “Add Python.exe to Path” and click on the small red “x.” Choose the “Will be installed on local hard drive” option then press“Next.” Now that you have completed the installation process, click on “Finish.
- 16. Setup the Path Variable Begin by opening the start menu and typing in “environment” and select the option called “Edit the system environment variables.” When the “System Properties” windowappears, click on “Environment Variables…” Once you have the “EnvironmentVariables” windowopen, direct yourfocus to the bottom half. You will notice that it controls all the “System Variables” rather than just this associated with your user. Click on “New…” to create a new variable for Python. Simply enter a name for your Path and the code shown below. For the purposesof this example we have installed Python2.7.3, so we will call the path: “Pythonpath.” The string that you will need to enter is: “C:Python27;C:Python27Scripts;”
- 17. Running The Python IDE Now that we have successfully completed the installation process and added our “EnvironmentVariable,” you are ready to create your first basic Pythonscript. Let’s begin by openingPython’sGUI by pressing “Start” and typing “Python” and selecting the “IDLE (Python GUI).”
- 18. Once the GUI is open, we will begin by using the simplest directive possible. This is the “print” directive which simply printswhatever you tell it to, into a new line. Start by typing a print directive like the one shown in the image below or copy and paste this text then press “Enter”: print (“Congratulations on executing your first print directive!”) Python CodeExecution
- 19. Python’s traditional runtime execution model: source code you type is translated to byte code, whichis then run by the PythonVirtual Machine. Your code is automatically compiled, but then it is interpreted. Source code extension is.py Byte code extension is .pyc (compiled pythoncode)
- 20. Characteristics of Python Interpreted Language: Python is processed at runtime by Python Interpreter • Easy to read: Python source-code is clearly defined and visible to the eyes. • Portable: Python codes can be run on a wide variety of hardware platforms having the same interface. • Extendable: Users can add low level-modules to Python interpreter. • Scalable: Python provides an improved structure for supporting large programs than shell-scripts. • Object-Oriented Language: It supports object-oriented features and techniques of programming. compile executoutput source code Hello.java byte code Hello.c lass
- 21. Data Type Data types determine whether an object can do something, or whether it just would not make sense. Other programming languages often determine whether an operation makes sense for an object by making sure the object can never be stored somewhere where the operation will be performed on the object (this type system is called static typing). Pythondoes not do that. Instead it stores the type of an object with the object, and checks when the operation is performed whether that operation makes sense for that object (this is called dynamic typing). Python has many native data types. Here are the important ones: Booleans are either True or False. Numbers can be integers (1 and 2), floats (1.1 and 1.2), fractions (1/2 and 2/3), or even complex numbers. Strings are sequences of Unicode characters, e.g. an HTML document. Bytes and byte arrays, e.g. a JPEG imagefile. Lists are ordered sequences of values. Tuples are ordered, immutable sequences of values. Sets are unordered bags of values. Chapter-: 3
- 22. Variables are nothingbut reserved memory locations to store values. Thismeans that when you create a variable you reserve some space in memory. Based on the data type of a variable, the interpreter allocates memory and decides what can be stored in the reserved memory. Therefore, by assigning different data types to variables, you can store integers,decimals or characters in these variables. Ex: counter =100 # An integer assignment miles = 1000.0 # A floatingpoint name = "John" # Astring String In programmingterms, we usually call text a string. When you think of a string as a collection of letters, the term makes sense. All the letters, numbers,and symbols in this book could be a string. For that matter, your name could be a string, and so could your address. Creating Strings In Python,we create a string by putting quotesaroundtext. For example, we could take our otherwise useless • "hello"+"world" "helloworld" # concatenatio n • "hello"*3 "hellohellohello" # repetition • "hello"[0] "h" # indexing • "hello"[-1] "o" # (from end) Variable
- 23. • "hello"[1:4] "ell" # slicing • len("hello") 5 # size • "hello" < "jello" 1 # compari son • "e" in "hello" 1 # search Python Operator Arithmetic Operator Operator Meaning Example + Add two operands or unary plus x + y +2 - Subtract right operand from the left or unary minus x - y -2 * Multiply twooperands x * y / Divide left operand by the right one (always results into float) x / y % Modulus - remainder of the division of left operand by the right x % y (remainder of x/y) // Floor division - division that results into whole number adjusted to the left in the number line x // y ** Exponent - left operand raised to the power ofright x**y (x to the power y)
- 24. Comparison Operator > Greater that - True if left operandis greater than theright x > y < Less that - True if left operand is less than the right x < y == Equal to - True if both operandsareequal x == y != Not equal to - True if operandsare notequal x != y >= Greater than or equal to - True if left operand is greater than or equal to the right x >= y <= Less than or equal to - True if left operandis less than or equal to the right x <= y Logical Operator Operator Meaning Example and True if both the operands aretrue x and y or True if either of the operands is true x or y not True if operand is false (complements the operand) not x
- 25. Tuples A tuple is a sequence of immutable Pythonobjects. Tuples are sequences, just like lists. The differences between tuples and lists are, the tuples cannot be changed unlike lists and tuples use parentheses, whereas lists use square brackets. Creating a tuple is as simple as putting different comma-separated values. Optionally you can put these comma-separated values between parentheses also. For example− tup1 = ('physics','chemistry', 1997,2000); tup2 = (1, 2, 3, 4, 5 ); tup3 = "a", "b", "c", "d"; Accessing Values in Tuples: To access values in tuple, use the squarebrackets for slicing along with the index or indices to obtain value available at that index. For example− tup1 = ('physics','chemistry', 1997,2000); tup2 = (1, 2, 3, 4, 5, 6, 7 ); print "tup1[0]: ",tup1[0] print "tup2[1:5]: ",tup2[1:5] When the above code is executed, it produces the following result − tup1[0]: physics tup2[1:5]: [2, 3, 4, 5] Basic TuplesOperations Tuples respond to the + and * operators much like strings; they mean concatenation and repetition here too, except that the result is a new tuple, not a string. In fact, tuples respond to all of the general sequence operations we used on strings in the prior chapter − Chapter-: 4
- 26. Python Expression Results Description len((1, 2, 3)) 3 Length (1, 2, 3) + (4, 5, 6) (1, 2, 3, 4, 5, 6) Concatenation ('Hi!',) *4 ('Hi!', 'Hi!', 'Hi!','Hi!') Repetition 3 in (1, 2, 3) True Membership for x in (1, 2, 3): print x, 1 23 Iteration Built-in Tuple Functions Pythonincludes the following tuple functions − SN Function withDescription 1 cmp(tuple1, tuple2) Compares elements of bothtuples. 2 len(tuple) Gives the total length of the tuple. 3 max(tuple) Returns item from the tuple with max value. 4 min(tuple) Returns item from the tuple with min value. 5 tuple(seq) Converts a list into tuple.
- 27. The list is a mostversatile datatype available in Pythonwhichcan be written as a list of comma-separated values (items) between square brackets. Important thing about a list is that items in a list need not be of the same type. Creating a list is as simple as putting different comma-separated values between square brackets.For example − list1 = ['physics','chemistry', 1997, 2000]; list2 = [1, 2, 3, 4, 5 ]; list3 = ["a", "b", "c", "d"]; Similar to string indices, list indices start at 0, and lists can be sliced, concatenated and soon. Accessing Values in Lists: To access values in lists, use the squarebrackets for slicing along with the index or indices to obtain value available at that index. For example− list1 = ['physics','chemistry', 1997, 2000]; list2 = [1, 2, 3, 4, 5, 6, 7 ]; print "list1[0]: ",list1[0] print "list2[1:5]:", list2[1:5] Output:list1[0]: physics list2[1:5]: [2, 3, 4, 5] Update: list = ['physics', 'chemistry', 1997, 2000]; print "Value available at index 2 :" print list[2] list[2] =2001; print "New value available at index 2 :" print list[2] List:
- 28. Output:Value available at index 2 :1997 New value available at index 2 :2001 Delete: list1 = ['physics', 'chemistry', 1997,2000]; print list1 del list1[2]; print "After deleting value at index 2 :" print list1 ['physics', 'chemistry', 1997,2000] Output:After deleting value at index 2 : ['physics', 'chemistry',2000] Basic ListOperation Python Expression Results Description len([1, 2, 3]) 3 Length [1, 2, 3] + [4, 5, 6] [1, 2, 3, 4, 5, 6] Concatenation ['Hi!'] *4 ['Hi!', 'Hi!', 'Hi!','Hi!'] Repetition 3 in [1, 2, 3] True Membership for x in [1, 2, 3]: print x, 1 2 3 Iteration Built-in List Functions & Methods: SN Function with Description
- 29. File Handling in Python- Python too supports file handling and allows users to handle files i.e., to read and write files, along with many other file handling options, to operate on files. The concept of file handling has stretched over various other languages, but the implementation is either complicated or lengthy, but alike other concepts of Python, this concept here is also easy and short. Python treats file differently as text or binary and this is important. Each line of code includes a sequence of characters and they form text file. Each line of a file is terminated with a special character, called the EOL or End of Line characters like comma {,} or newline character. It ends the current line and tells the interpreter a new one has begun. Let’s start with Reading and Writing files. We use open () function in Python to open a file in read or write mode. As explained above, open ( ) will return a file object. To return a file object we use open () function along with two arguments, that accepts file name and the mode, whether to read or write. So, the syntax being: open(filename, mode). There are three kinds of mode, that Python provides and how files can be opened: • “ r “, for reading. • “ w “, for writing. • “ a “, for appending. • “ r+ “, for both reading and writing Ex-It is a notepad file (101.txt)
- 30. 1 cmp(list1, list2) Compares elements of both lists. 2 len(list) Gives the total length of the list. 3 max(list) Returns item from the list with max value. 4 min(list) Returns item from thelist with min value. 5 list(seq) Converts a tuple into list. Python includes following list methods SN Methods withDescription 1 list.append(obj) Appends object obj to list 2 list.count(obj) Returns count of how many times obj occurs in list 3 list.extend(seq) Appends the contents of seq to list 4 list.index(obj) Returns thelowest index in list that objappears 5 list.insert(index, obj) Inserts object obj into list at offsetindex 6 list.pop(obj=list[-1]) Removes and returns last object or obj from list 7 list.remove(obj) Removes object obj from list 8 list.reverse() Reverses objects of list inplace 9 list.sort([func]) Sorts objects of list, use compare func if given Built-in List Functions & Methods: SN
- 31. Loops Programminglanguages providevarious controlstructures thatallow for more complicated execution paths. A loop statement allows us to execute a statement or group ofstatements multiple times. The following diagram illustrates a loop statement− Pythonprogramminglanguageprovides followingtypes of loops to handle looping requirements. Loop Type Description while loop Repeats a statement or group of statements while a given condition is TRUE. It tests the condition before executing the loop body. for loop Executes a sequence of statements multiple times and abbreviates the code that manages the loop variable. Chapter-: 5
- 32. nested loops You can use one or more loop inside any another while, for or do..whileloop. Example: For Loop: >>> for mynum in [1, 2, 3, 4, 5]: print "Hello",mynum Hello 1 Hello 2 Hello 3 Hello 4 Hello 5 While Loop: >>> count =0 >>> while (count <4): print 'The count is:', count count = count +1 The count is:0 The count is: 1 The count is: 2 The count is:3
- 33. Decision making is anticipation of conditions occurring while execution of the programand specifying actions taken according to the conditions. Decision structures evaluate multiple expressions which produce TRUE or FALSE as outcome. You need to determine which action to take andwhich statements to execute if outcome is TRUE or FALSE otherwise. Pythonprogramminglanguage provides followingtypes of decision making statements. Click the following links to check theirdetail. Statement Description if statements An if statement consists of a boolean expression followed by one or more statements. if...else statements An if statement can be followed by an optional else statement, which executes when the boolean expression is FALSE. nested ifstatements You can use one if or else if statement inside another if or else if statement(s). Conditional Statements
- 34. If Statement: >>> state = “Texas” >>> if state == “Texas”: print “TX TX If...Else Statement: >>> if state == “Texas” print “TX” else: print “[inferiorstate]” If...Else...If Statement: >>> if name == “Paige” print “HiPaige!” elif name == “Walker”: print “HiWalker!” else: print “Imposter!” Function Function blocks begin with the keyword def followed by the function name and parentheses ( ( )). Any input parameters or arguments should be placed within these parentheses. You can also define parameters inside these parentheses. Example:
- 35. The first statement of a function can bean optional statement - the documentation string of the function. The code block within every function starts with a colon (:) and is indented. The statement return [expression] exits a function, optionally passing back an expression to the caller. A return statement with no arguments is the same as return None. Syntex: def functionname( parameters): "function_docstring" function_suite return [expression] Example: 1. def printme( str ): "This prints a passed stringinto this function" print str return 2. # Function definition ishere def printme( str ): "This prints a passed string into this function" print str return; # Now you can call printmefunction printme("I'm first call to user defined function!") printme("Again second call to the samefunction")
- 36. Science - Bioinformatics SystemAdministration -Unix -Web logic -Web sphere Web ApplicationDevelopment -CGI Testing scripts What Can We do With Python? Systemprogramming GraphicalUser InterfaceProgramming InternetScripting Component Integration DatabaseProgramming Gaming,Images, XML, Robot and more Who Uses PythonToday? Python is being applied in real revenue-generating products by real companies. Google makes extensive use of Pythonin its web searchsystem,and employs Python’screator. Intel, Cisco, Hewlett-Packard, Seagate, Qualcomm, and IBM use Python for hardwaretesting. Chapter-: 6 Scope of Python
- 37. ESRI uses Pythonas an end-user customizationtool for its popular GIS mapping products. The YouTube video sharingserviceis largely written in Python. Why Do People Use Python? The following primaryfactors cited by Python users seem to be these: Python isobject-oriented o Structure supports such concepts as polymorphism, operation overloading, and multiple inheritance. Indentation o Indentation is one of the greatest future in Python. It's free (opensource) o Downloading and installing Pythonis free and easy o Source code is easilyaccessible It's powerful o Dynamictyping o Built-in types and tools o Libraryutilities o Third party utilities (e.g. Numeric, NumPy,SciPy) o Automatic memorymanagement It's portable o Pythonruns virtuallyevery majorplatform used today o As long as you have a compatible Python interpreter installed, Pythonprograms willrun in exactly the same manner, irrespective of platform. Python is being applied in real revenue-generating products by real companies. Google makes extensive use of Pythonin its web searchsystem, and employs Python’screator. Intel, Cisco, Hewlett-Packard, Seagate, Qualcomm, and IBM use Python for hardwaretesting Who Uses Python Today?
- 38. I believe the trial has shown conclusivelythat it is both possible and desirable to use Pythonas the principal teaching language: o It is Free (as in both cost and sourcecode). o It is trivial to install on a Windows PC allowing students to take their interest further. For many the hurdle of installing a Pascalor C compiler on a Windows machine is either too expensive or too complicated; o It is a flexible tool that allows both the teaching of traditional procedural programming and modern OOP; It can be used to teach a large number of transferableskills; o It is a real-world programminglanguagethat can be and is used in academia and the commercialworld; o It appears to be quicker to learn and, in combination with its many libraries, this offers the possibility of more rapid student development allowing the course to be made more challenging and varied; o and mostimportantly, its clean syntax offers increased understanding and enjoyment for students; Conclusion