Introduction to Python Programming – Part I.pptx

Introduction to Python
Programming – Part I
Introduction to Internet of Things
1

Why Python?
2
 Python is a versatile language which is easy to script and easy to
read.
 It doesn’t support strict rules for syntax.
 Its installation comes with integrated development environment
for programming.
 It supports interfacing with wide ranging hardware platforms.
 With open-source nature, it forms a strong backbone to build large
applications.

Python IDE
3
 Python IDE is a free and open source software that is used to
write codes, integrate several modules and libraries.
 It is available for installation into PC with Windows, Linux and
Mac.
 Examples: Spyder, PyCharm, etc.

Starting with Python
4
 Simple printing statement at the python interpreter prompt,
>>> print “Hi, Welcome to python!”
Output: Hi, Welcome to python!
 To indicate different blocks of code, it follows rigid indentation.
if True:
print “Correct"
else:
print “Error"

Data-types in
Python
5
 There are 5 data types in Python:
 Numbers
x, y, z = 10, 10.2, " Python "
 String
x = ‘This is Python’
print x
print x[0]
print x[2:4]
>>This is Python
>>T
>>is

Data-types in Python
(contd..)
6
 List
x = [10, 10.2, 'python']
 Tuple
 Dictionary
d = {1:‘item','k':2}

Controlling
Statements
7
 if (cond.):
statement 1
statement 2
elif (cond.):
statement 1
statement 2
else:
statement 1
statement 2
 while (cond.):
statement 1
statement 2
 x = [1,2,3,4]
for i in x:
statement 1
statement 2

Controlling Statements
(contd..)
8
 Break
for s in "string":
if s == ‘n':
break
print (s)
print
“End”
 Continue
for s in "string":
if s == ‘y':
continue
print (s)
print “End”

Functions in Python
9
# Defining the function
 Defining a function
 Without return value
def funct_name(arg1, arg2, arg3):
statement 1
statement 2
 With return value
def funct_name(arg1, arg2, arg3):
# Defining the function
statement 1
statement 2
return x
# Returning the value

Functions in
Python
Introduction to Internet of Things 10
 Calling a function
def example (str):
print (str + “!”)
example (“Hi”) # Calling the function
Output:: Hi!

Functions in Python
(contd..)
 Example showing function returning multiple values
def greater(x, y):
if x > y:
return x, y
else:
return
y, x
val = greater(10,
100) print(val)
Output:: (100,10)

Functions as Objects
 Functions can also be assigned and reassigned to the variables.
 Example:
def add (a,b)
return a+b
print (add(4,6))
c = add(4,6)
print c
Output:: 10 10

Variable Scope in
Python
Global variables:
These are the variables declared out of any function , but can be
accessed inside as well as outside the function.
Local variables:
These are the ones that are declared inside a function.

Example showing Global
Variable
g_var = 10
def example():
l_var = 100
print(g_var)
example() # calling the function
Output:: 10

Example showing
Variable Scope
var = 10
def example():
var = 100
print(var)
# calling the function
example()
print(var)
Output:: 100
10

Modules in Python
 Any segment of code fulfilling a particular task that can be
used commonly by everyone is termed as a module.
 Syntax:
import module_name #At the top of the code
using module_name.var #To access functions and values
with ‘var’ in the module

Modules in Python
(contd..)
 Example:
import random
for i in range(1,10):
val = random.randint(1,10)
print (val)
Output:: varies with each execution

Modules in Python
(contd..)
 We can also access only a particular function from a module.
 Example:
from math import pi
print (pi)
Output:: 3.14159

Exception Handling in
Python
 An error that is generated during execution of a program, is
termed as exception.
 Syntax:
try:
statements
except _Exception_:
statement
s else:
statemen
ts

Exception Handling in Python
(contd..)
 Example:
while True:
try:
n = input ("Please enter an integer: ")
n = int (n)
break
except ValueError:
print
"No valid
integer! "
print “It is an
integer!"

Example Code: to check number is prime or not
x = int (input("Enter a number: "))
def prime (num):
if num > 1:
for i in
range(2,num):
if (num % i)
== 0:
print (num,"is not a prime number")
print (i,“is a factor of”,num)
break
else:
print(num,"is a prime number")
else:
print(num,"is not a prime number")
prime (x)

Introduction to Python
Programming – Part II
1

File Read Write
Operations
2
 Python allows you to read and write files
 No separate module or library required
 Three basic steps
 Open a file
 Read/Write
 Close the file

File Read Write Operations
(contd..)
3
Opening a File:
 Open() function is used to open a file, returns a file object
open(file_name, mode)
 Mode: Four basic modes to open a file
r: read mode
w: write mode
a: append mode
r+: both read
and write mode

(contd..)
4
Read from a file:
 read(): Reads from a file
file=open(‘data.txt’, ‘r’)
file.read()
Write to a file:
 Write(): Writes to a file
file=open(‘data.txt’, ‘w’)
file.write(‘writing to the file’)

(contd..)
5
Closing a file:
 Close(): This is done to ensure that the file is free to use for other resources
file.close()
Using WITH to open a file:
 Good practice to handle exception while file read/write operation
 Ensures the file is closed after the operation is completed, even if an exception is
encountered
with open(“data.txt","w") as file:
file.write(“writing to the text file”)
file.close()

File Read Write Operations code +
image
6
with open("PythonProgram.txt","w") as file:
file.write("Writing data")
file.close()
with open("PythonProgram.txt","r") as file:
f=file.read()
print('Reading from the filen')
print (f)
file.close()

(contd..)
7
Comma Separated Values Files
 CSV module supported for CSV files
Read:
with open(file, "r") as csv_file:
reader = csv.reader(csv_file)
print("Reading from the CSV Filen")
for row in reader:
print(" ".join(row))
csv_file.close()
Write:
data = ["1,2,3,4,5,6,7,8,9".split(",")]
file = "output.csv"
with open(file, "w") as csv_file:
writer = csv.writer(csv_file, delimiter=',')
print("Writing CSV")
for line in data:
writer.writerow(line)
csv_file.close()

(contd..)
8

Image Read/Write
Operations
9
 Python supports PIL library for image related operations
 Install PIL through PIP
sudo pip install pillow
PIL is supported till python version 2.7. Pillow supports the 3x version of
python.

Image Read/Write
Operations
Reading Image in Python:
 PIL: Python Image Library is used to work with image files
from PIL import Image
 Open an image file
image=Image.open(image_name)
 Display the image
image.show()

Image Read/Write
Operations (contd..)
Resize(): Resizes the image to the specified size
image.resize(255,255)
Rotate(): Rotates the image to the specified degrees, counter clockwise
image.rotate(90)
Format:
Size:
Mode:
Gives the format of the image
Gives a tuple with 2 values as width and height of the image, in pixels
Gives the band of the image, ‘L’ for grey scale, ‘RGB’ for true colour image
print(image.format, image.size, image.mode)

Image Read/Write Operations
(contd..)
Convert image to different mode:
 Any image can be converted from one mode to ‘L’ or ‘RGB’
mode
conv_image=image.convert(‘L’)
 Conversion between modes other that ‘L’ and ‘RGB’ needs
conversion into any of these 2 intermediate mode

Output
Converting a sample image to Grey Scale

Output

Networking in Python
 Python provides network services for client server model.
 Socket support in the operating system allows to implement clients
and servers for both connection-oriented and connectionless
protocols.
 Python has libraries that provide higher-level access to specific
application-level network protocols.

Networking in Python
(contd..)
 Syntax for creating a socket:
s = socket.socket (socket_family, socket_type, protocol=0)
socket_family − AF_UNIX or AF_INET
socket_type − SOCK_STREAM or SOCK_DGRAM
protocol − default ‘0’.

Example - simple server
 The socket waits until a client connects to the port, and then returns a
connection object that represents the connection to that client.
import socket
import sys
# Create a
TCP/IP socket
sock =
socket.socket(
socket.AF_IN
ET,
socket.SOCK_
STREAM)
# Bind the socket to the port
server_address = ('10.14.88.82', 2017)
print >>sys.stderr, 'starting up on %s port %s' % server_address
sock.bind(server_address)

Example - simple server
(contd..)
# Listen for incoming connections
sock.listen(1)
connection, client_address = sock.accept()
#Receive command
data = connection.recv(1024)
print(data)
sock.close()

Example - simple client
import socket
import sys
# Create a
TCP/IP socket
client_socket
=
socket.socket(
socket.AF_IN
ET,
socket.SOCK_
STREAM)
#Connect to Listener socket
client_socket.connect(("10.14.88.82", 2017))
print>>sys.stderr,'Connection Established'
#Send command
client_socket.send('Message to the server')
print('Data sent successfully')

Code Snapshot

Output

Introduction to Python Programming – Part I.pptx

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