Python was created by Guido van Rossum, and released in 1991.
It is a general-purpose computer programming language. It is a high-level, object-oriented language which can run equally on different platforms such as Windows, Linux, UNIX, and Macintosh. Its high-level built-in data structures, combined with dynamic typing and dynamic binding. It is widely used in data science, machine learning and artificial intelligence domain.
It is easy to learn and require less code to develop the applications.
It is widely used for:
Python is used in various software domains some application areas are given below.
Python provides various web frameworks to develop web applications. The popular python web frameworks are Django, Pyramid, Flask.
Python’s standard library supports for E-mail processing, FTP, IMAP, and other Internet protocols.
Python’s SciPy and NumPy helps in scientific and computational application development.
Python’s Tkinter library supports to create a desktop based GUI applications.
PEP 8 stands for Python Enhancement Proposal, it can be defined as a document that helps us to provide the guidelines on how to write the Python code. It is basically a set of rules that specify how to format Python code for maximum readability. It was written by Guido van Rossum, Barry Warsaw and Nick Coghlan in 2001.
Literals can be defined as a data which is given in a variable or constant. Python supports the following literals:
String literals are formed by enclosing text in the single or double quotes. For example, string literals are string values.
# in single quotes
single = ‘JavaTpoint’
# in double quotes
double = “JavaTpoint”
# multi-line String
multi = ””’Java
Python supports three types of numeric literals integer, float and complex.
# Integer literal
a = 10
b = 12.3
x = 3.14j
Boolean literals are used to denote Boolean values. It contains either True or False.
p = (1 == True)
q = (1 == False)
r = True + 3
s = False + 7
print(“p is”, p)
print(“q is”, q)
p is True
q is False
Python contains one special literal, that is, ‘None’. This special literal is used for defining a null variable. If ‘None’ is compared with anything else other than a ‘None’, it will return false.
word = None
A function is a section of the program or a block of code that is written once and can be executed whenever required in the program. A function is a block of self-contained statements which has a valid name, parameters list, and body. Functions make programming more functional and modular to perform modular tasks. Python provides several built-in functions to complete tasks and also allows a user to create new functions as well.
There are three types of functions:
Built-In Functions: copy(), len(), count() are the some built-in functions.
User-defined Functions: Functions which are defined by a user known as user-defined functions.
Anonymous functions: These functions are also known as lambda functions because they are not declared with the standard def keyword.
Example: A general syntax of user defined function is given below.
def function_name(parameters list):
Python zip() function returns a zip object, which maps a similar index of multiple containers. It takes an iterable, convert into iterator and aggregates the elements based on iterables passed. It returns an iterator of tuples.
iterator1, iterator2, iterator3: These are iterator objects that are joined together.
It returns an iterator from two or more iterators.
Python’s constructor: _init__ () is the first method of a class. Whenever we try to instantiate an object __init__() is automatically invoked by python to initialize members of an object. We can’t overload constructors or methods in Python. It shows an error if we try to overload.
def __init__(self, name):
self.name = name
def __init__(self, name, email):
self.name = name
self.email = email
# This line will generate an error
#st = student(“rahul”)
# This line will call the second constructor
st = student(“rahul”, “email@example.com”)
print(“Name: “, st.name)
print(“Email id: “, st.email)
The user can use the remove() function to delete a specific object in the list.
[3, 5, 7, 3, 9, 3]
After removal: [5, 7, 3, 9, 3]
If you want to delete an object at a specific location (index) in the list, you can either use del or pop.
[3, 5, 7, 3, 9, 3]
After deleting: [3, 5, 3, 9, 3]
It is a string’s function which converts all uppercase characters into lowercase and vice versa. It is used to alter the existing case of the string. This method creates a copy of the string which contains all the characters in the swap case. If the string is in lowercase, it generates a small case string and vice versa. It automatically ignores all the non-alphabetic characters. See an example below.
it is in lowercase.
IT IS IN UPPERCASE.
To remove the whitespaces and trailing spaces from the string, Python providies strip([str]) built-in function. This function returns a copy of the string after removing whitespaces if present. Otherwise returns original string.
After stripping all have placed in a sequence:
To remove leading characters from a string, we can use lstrip() function. It is Python string function which takes an optional char type parameter. If a parameter is provided, it removes the character. Otherwise, it removes all the leading spaces from the string.
After stripping all leading whitespaces:
After stripping, all the whitespaces are removed, and now the string looks like the below:
The join() is defined as a string method which returns a string value. It is concatenated with the elements of an iterable. It provides a flexible way to concatenate the strings. See an example below.
This method shuffles the given string or an array. It randomizes the items in the array. This method is present in the random module. So, we need to import it and then we can call the function. It shuffles elements each time when the function calls and produces different output.
['Z', 'Y', 'X', 'W', 'V', 'U']
After the first shuffle of LIST1:
['V', 'U', 'W', 'X', 'Y', 'Z']
After the second shuffle of LIST1:
['Z', 'Y', 'X', 'U', 'V', 'W']
The break statement is used to terminate the execution of the current loop. Break always breaks the current execution and transfer control to outside the current block. If the block is in a loop, it exits from the loop, and if the break is in a nested loop, it exits from the innermost loop.
Python Break statement flowchart.
A tuple is a built-in data collection type. It allows us to store values in a sequence. It is immutable, so no change is reflected in the original data. It uses () brackets rather than  square brackets to create a tuple. We cannot remove any element but can find in the tuple. We can use indexing to get elements. It also allows traversing elements in reverse order by using negative indexing. Tuple supports various methods like max(), sum(), sorted(), Len() etc.
To create a tuple, we can declare it as below.
(2, 4, 6, 8)
It is immutable. So updating tuple will lead to an error.
TypeError: 'tuple' object does not support item assignment
(2, 4, 6, 8)
The Python provides libraries/modules that enable you to manipulate text files and binary files on the file system. It helps to create files, update their contents, copy, and delete files. The libraries are os, os.path, and shutil.
Here, os and os.path – modules include a function for accessing the filesystem
while shutil – module enables you to copy and delete the files.
Python provides four modes to open files. The read-only (r), write-only (w), read-write (rw) and append mode (a). ‘r’ is used to open a file in read-only mode, ‘w’ is used to open a file in write-only mode, ‘rw’ is used to open in reading and write mode, ‘a’ is used to open a file in append mode. If the mode is not specified, by default file opens in read-only mode.