ST. ANNE’S
           COLLEGE OF ENGINEERING AND TECHNOLOGY
ANGUCHETTYPALAYAM, PANRUTI – 607 110

DEPARTMENT OF COMPUTER SCIENCE AND ENGINEERING

I SEMESTER - R 2017

GE8161– PROBLEM SOLVING AND PYTHON PROGRAMMING LABORATORY

LABORATORY MANUAL

Name	: _______________________________________

Register No	: _______________________________________

Department	: _______________________________________

 GE 8161 – PROBLEM SOLVING AND 
PYTHON PROGRAMMING LABORATORY

SYLLABUS

COURSE OBJECTIVES

To write, test, and debug simple Python programs.

To implement Python programs with conditionals and loops.

Use functions for structuring Python programs.

Represent compound data using Python lists, tuples, dictionaries.

Read and write data from/to files in Python.

LIST OF EXPERIMENTS:
1.Compute the GCD of two numbers.

2.	Find the square root of a number (Newton’s method)

3.	Exponentiation (power of a number)
4.	Find the maximum of a list of numbers

5.	Linear search and Binary search
6.	Selection sort, Insertion sort
7.	Merge sort
8.	First n prime numbers

9.	Multiply matrices

10.	Programs that take command line arguments (word count)
11.	Find the most frequent words in a text read from a file
12.	Simulate elliptical orbits in Pygame

13.Simulate bouncing ball in Pygame

COURSE OUTCOMES

Upon completion of the course, students will be able to:

Write, test, and debug simple Python programs.

Implement Python programs with conditionals and loops.

Develop Python programs step-wise by defining functions and calling them.

Use Python lists, tuples, dictionaries for representing compound data.

Read and write data from/to files in Python.

GE 8161 – PROBLEM SOLVING AND 
PYTHON PROGRAMMING LABORATORY

CONTENTS

S.No.	Date	Name of the Experiment	Faculty sign	
1.		Compute the GCD of two numbers		
2.		Find the square root of a number (Newton’s method)
		
3.		Exponentiation (power of a number)		
4		Find the maximum of a list of numbers		
5A		Linear search		
5B		Binary search		
6A		Selection Sort		
7

		Merge sort	

	
8		First n prime numbers		

9

		Multiply matrices		
10		Programs that take command line arguments (word count)		
11		11 Find the most frequent words in a text read from a file		
12		Simulate elliptical orbits in Pygame		
13		Simulate bouncing ball in Pygame		

Ex. No. :01			
			
Date:	GCD OF TWO NUMBERS		

Aim:

To write a Python program to find GCD of two numbers.

Algorithm:

1.	Define a function named computeGCD()

2.	Find the smallest among the two inputs x and y

3.	Perform the following step till smaller+1

Check if ((x % i == 0) and (y % i == 0)), then	assign GCD=i

4.	Print the value of gcd

Program:

def computeGCD(x, y):

if x > y:

smaller = y
else:

smaller = x

for i in range(1, smaller+1):

if((x % i == 0) and (y % i == 0)):
gcd = i

return gcd

num1 = 54

num2 = 24

#	take input from the user
#	num1 = int(input("Enter first number: "))

#	num2 = int(input("Enter second number: "))

print("The GCD. of", num1,"and", num2,"is", computeGCD(num1, num2))

Output :

The GCD of 54 and 24 is 6

Result:

Thus the Python program to compute GCD of two numbers is executed successfully and the output is verified.

			
Ex. No. :02			
Date:	SQUARE ROOT OF A NUMBER		

Aim:

To write a Python Program to find the square root of a number by Newton’s Method.

Algorithm:

1.	Define a function named newtonSqrt().

2.	Initialize approx as 0.5*n and better as 0.5*(approx.+n/approx.)

3.	Use a while loop with a condition better!=approx to perform the following,

i.	Set approx.=better

ii.	Better=0.5*(approx.+n/approx.)

4.	Print the value of approx

Program:

def newtonSqrt(n):

approx = 0.5 * n

better = 0.5 * (approx + n/approx)

while better != approx:

approx = better
	
better = 0.5 * (approx + n/approx)

return approx

print('The square root is' ,newtonSqrt(81))

Output:

The square root is 9

Result:

Thus the Python program for finding the square root of a given number by Newton’s Method is executed successfully and the output is verified.

	Ex. No. : 03						

	Date:		EXPONENTIATION OF A NUMBER				

Aim:

To write a Python program to find the exponentiation of a number.

Algorithm:

1.	Define a function named power()

2.	Read the values of base and exp

3.	Use ‘if’ to check if exp is equal to 1 or not i. if exp is equal to 1, then return base
ii.if exp is not equal to 1, then return (base*power(base,exp-1))

4.	Print the result

Program:

def power(base,exp):

if(exp==1):

return(base)

if(exp!=1):

return(base*power(base,exp-1))

base=int(input("Enter base: "))

exp=int(input("Enter exponential value: "))

print("Result:",power(base,exp))

Output:

Enter base: 7

Enter exponential value: 2

Result:49

Result:

Thus the Python program to find the exponentiation of a number is executed successfully and the output is verified.

  
  Ex. No. :04
FINDING MAXIMUM FROM A LIST OF NUMBERS
  Date:

Aim:

To write a Python Program to find the maximum from a list of numbers.

Algorithm:

1.	Create an empty list named l

2.	Read the value of n

3.	Read the elements of the list until n

4.	Assign l[0] as maxno

5.	If l[i]>maxno then set maxno=l[i]

6.	Increment i by 1

7.	Repeat steps 5-6 until i<n

8.	Print the value of maximum number

Program:

l=[]

n=int(input("enter the upper limit"))

for i in range(0,n):

a=int(input("enter the numbers"))

l.append(a)

maxno=l[0]

for i in range(0,len(l)):

if l[i]>maxno:

maxno=l[i]

print("The maximum number is %d"%maxno)

Output:

Enter the upper limt 3

Enter the numbers 6

Enter the numbers 9
Enter the numbers 90

The maximum number is 90

Result:

Thus a Python Program to find the maximum from the given list of numbers is successfully executed and the output is verified.

Ex. No. : 5(a)			
Date:	LINEAR SEARCH		

Aim:

To write a Python Program to perform Linear Search Algorithm:

1.	Read n elements into the list

2.	Read the element to be searched

3.	If alist[pos]==item, then print the position of the item

4.	Else increment the position and repeat step 3 until pos reaches the length of the list

Program:

def search(alist,item):

pos=0

found=False

stop=False

while pos<len(alist) and not found and not stop:

if alist[pos]==item:

found=True

print("element found in position",pos)

else:

if alist[pos]>item:

stop=True

else:

pos=pos+1

return found

a=[]

n=int(input("enter upper limit"))

for i in range(0,n):

e=int(input("enter the elements"))

a.append(e)

x=int(input("enter element to search"))

search(a,x)

Output:

Enter upper limit 5

Enter the elements 6

Enter the elements 45

Enter the elements 2

Enter the elements 61

Enter the elements 26

Enter element to search 6

Element found in position 1

Result:

Thus the Python Program to perform linear search is executed successfully and the output is verified.

	EX. No. : 5(b)						

	Date:		BINARY SEARCH				

Aim:

To write a Python Program to perform binary search.

Algorithm:

1.	Read the search element

2.	Find the middle element in the sorted list

3.	Compare the search element with the middle element

i.	if both are matching, print element found

ii.	else then check if the search element is smaller or larger than the middle element

4.	If the search element is smaller than the middle element, then repeat steps 2 and 3 for the left sublist of the middle element

5.	If the search element is larger than the middle element, then repeat steps 2 and 3 for the right sublist of the middle element

6.	Repeat the process until the search element if found in the list

7.	If element is not found, loop terminates

Program:

def bsearch(alist,item):

first=0

last=len(alist)-1

found=False

while first<=last and not found:

mid=(first+last)//2

if alist[mid]==item:

found=True

print("element found in position",mid)

else:

if item<alist[mid]:

last=mid-1

else:

first=mid+mid-1

return found

a=[]

n=int(input("enter upper limit"))

for i in range(0,n):

e=int(input("enter the elements"))

a.append(e)

x=int(input("enter element to search"))

bsearch(a,x)

Output:

enter upper limit 6

enter the elements 2

enter the elements 3

enter the elements 5

enter the elements 7

enter the elements 14

enter the elements	25

enter element to search 5

element found in position 2

Result:

Thus the Python Program to perform binary search is executed successfully and the output is verified

Ex. No. : 6(a)			
Date:	SELECTION SORT		

Aim:

To write a Python Program to perform selection sort.

Algorithm:

1.	Create a function named selectionsort

2.	Initialise pos=0

3.	If alist[location]>alist[pos] then perform the following till i+1,

4.	Set pos=location

5.	Swap alist[i] and alist[pos]

6.	Print the sorted list

Program:

def selectionSort(alist):

for i in range(len(alist)-1,0,-1):

pos=0

for location in range(1,i+1):

if alist[location]>alist[pos]:

pos= location

temp = alist[i]

alist[i] = alist[pos]

alist[pos] = temp

alist = [54,26,93,17,77,31,44,55,20]

selectionSort(alist)

print(alist)

Output:

[17, 20, 26, 31, 44, 54, 55, 77, 93]

Result:

Thus the Python Program to perform selection sort is successfully executed and the output is verified.

Ex. No. : 6(b)
INSERTION SORT
Date:

Aim:

To write a Python Program to perform insertion sort.

Algorithm:

1.	Create a function named insertionsort

2.	Initialise currentvalue=alist[index] and position=index

3.	while position>0 and alist[position-1]>currentvalue, perform the following  till len(alist)

4.	alist[position]=alist[position-1]

5.	position = position-1

6.	alist[position]=currentvalue

7.	Print the sorted list

Program:

def insertionSort(alist):

for index in range(1,len(alist)):

currentvalue = alist[index]

position = index

while position>0 and alist[position-1]>currentvalue:

alist[position]=alist[position-1]

position = position-1

alist[position]=currentvalue

alist = [54,26,93,17,77,31,44,55,20]

insertionSort(alist)

print(alist)

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Output:

[17, 20, 26, 31, 44, 54, 55, 77, 93]

Result:

Thus the Python program to perform insertion sort is successfully executed and the output is verified.

GE8161	

               MERGESORT

Ex.No. 7

Date:

Aim:

To write a Python Program to perform Merge sort.

Algorithm:

1.	Create  a function named  mergesort

2.	Find the mid of the list

3.	Assign lefthalf = alist[:mid] and righthalf = alist[mid:]

4.	Initialise i=j=k=0

5.	while i < len(lefthalf) and j < len(righthalf), perform the following if lefthalf[i] < righthalf[j]:

alist[k]=lefthalf[i]

Increment i

else

alist[k]=righthalf[j]

Increment j

Increment k

6.	while i < len(lefthalf),perform the following alist[k]=lefthalf[i]

7.	while j < len(righthalf), perform the following alist[k]=righthalf[j]

Increment j Increment k

8.	Print the sorted list

	

Program:

def mergeSort(alist):

     print("Splitting ,alist)               if len(alist)>1:

mid = len(alist)//2 lefthalf = alist[:mid] righthalf = alist[mid:] mergeSort(lefthalf) mergeSort(righthalf) i=j=k=0

while i < len(lefthalf) and j < len(righthalf): if lefthalf[i] < righthalf[j]:

alist[k]=lefthalf[i]

i=i+1

else:

alist[k]=righthalf[j]

j=j+1

k=k+1

while i < len(lefthalf): alist[k]=lefthalf[i] i=i+1

k=k+1

while j < len(righthalf): alist[k]=righthalf[j] j=j+1

k=k+1 #print("Merging ",alist)

alist = [54,26,93,17,77,31,44,55,20]

mergeSort(alist)

print(alist)

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Output:

[17, 20, 26, 31, 44, 54, 55, 77, 93]

Result:

Thus the Python program to perform merge sort is successfully executed and the output is
verifie

GE8161	

Ex. No. : 8
FIRST N PRIME NUMBERS
Date:

Aim:

To write a Python program to find first n prime numbers.

Algorithm:

1.	Read the value of  n

2.	for num in range(0,n + 1), perform the following

3.	if num%i is 0 then break else print the value of num

4.	Repeat step 3 for i in range(2,num)

Program:

n = int(input("Enter the upper limit: "))

print("Prime numbers are")

for num in range(0,n + 1):

#	prime numbers are greater than 1 if num > 1:

for i in range(2,num): if (num % i) == 0:

break
else:

print(num)

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Output:

Enter the upper limit:100

Prime numbers are

2
3

5

7

11
13

17

19

23
29

31

37

41
43

47

53

59
61

67

71

73
79

83

89

97

Result:

Thus the Python Program to find the first n prime numbers is executed successfully and the output is verified.

Ex. No. : 9
MATRIX MULTIPLICATION
Date:

Aim:

To write a Python program to multiply matrices.

Algorithm:

1.	Define two matrices X  and Y

2.	Create a resultant matrix named ‘result’

3.	for i in range(len(X)):

i.	for j in range(len(Y[0])):

a)	for k in range(len(Y))

b)	result[i][j] += X[i][k] * Y[k][j]

4.	for r in result, print the value of r

Program:

X = [[12,7,3],

[4 ,5,6],

[7 ,8,9]]

Y = [[5,8,1,2],

[6,7,3,0],

[4,5,9,1]]

result = [[0,0,0,0],

[0,0,0,0],

[0,0,0,0]]

for i in range(len(X)):

for j in range(len(Y[0])):

for k in range(len(Y)):

result[i][j] += X[i][k] * Y[k][j]

for r in result:

print(r)

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Output:

[114, 160, 60, 27]

[74, 97, 73, 14]

[119, 157, 112, 23]

Result:

Thus the Python program to multiply matrices is executed successfully and the output is

verified.

GE8161	

	Ex. No. :10						

	Date:		COMMAND LINE ARGUMENTS(WORD COUNT)				

Aim:

To write a Python program for command	line arguments.

Algorithm:

1.	Add arguments to find the words and lines

2.	Add the filename as argument

3.	Parse the arguments to get the values

4.	Format and print the words and lines

Program:

parser=argparse.ArgumentParser()

parser.add_argument('--words','-w',action='store_true')

parser.add_argument('--lines','-l',action='store_true')

parser.add_argument('filename')

args=parser.parse_args()

if args.words:

print("words {}".format(print_words(args.filename))

elif args.lines:

print("lines {}".format(print_lines(args.filename))

else:

print ("words {}".format(print_words(args.filename))

print("lines {}".format(print_lines(args.filename))

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Output:

python main.py –i input.txt

words 23

lines 1

Result:

Thus the Python program for command line arguments is executed successfully and the output is verified.

GE8161	

Ex. No. : 11			
Date:	FINDING MOST FREQUENT WORDS IN A TEXT READ FROM A FILE		

Aim:

To write a Python program to find the most frequent words in a text read from a file.

Algorithm:

1.	Read the filename

2.	Open the file in read mode

3.	Read each line from the file to count the lowers and words

4.	Read each  line from the file to replace the punctuations

5.	Split each line into words and count them

6.	Print the words and counts

Program:
def main():

filename=raw_input("enter the file").strip()

infile=open(filename,"r")

wordcounts={}
for line in infile:

processLine(line.lower(),wordcounts)

pairs=list(wordcounts.items())
items=[[x,y] for (y,x) in pairs]

items.sort()

for i in range(len(items)-1,len(items)-11,-1):

print(items[i][1]+"\t"+str(items[i][0]))
def processLine(line,wordcounts):

line=replacePunctuations(line)

words=line.split()

for word in words:
if word in wordcounts:

wordcounts[word]+=1

else:

wordcounts[word]=1
def replacePunctuations(line):

for ch in line:

if ch in "~@#$%^&*()_-+=<>?/.,:;!{}[]''":

line=line.replace(ch," ")
return line

main()

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Output:

Enter a filename:a.txt

Hi	1

How	1

Are	1

You	1

Result:

Thus the Python program to find the most frequent words in a text read from a file is executed successfully and the output is verified.

GE8161	

	Ex. No. : 12						

	Date:		SIMULATE ELLIPTICAL ORBITS IN PYGAME				

Aim:

To write a Python program to simulate elliptical orbits in Pygame.

Algorithm:

1.	Import the required packages

2.	Set up the colours for the elliptical orbits

3.	Define the parameters to simulate elliptical orbits

4.	Display the created orbits

Program:

import math

import random

import pygame

class Particle ():

def __init__ (self, x, y, colour=0x000000):

self.x = x

self.y = y

self.vx = 0

self.vy = 0

self.colour = colour

def apply_gravity (self, target):

dsqd = (self.x - target.x) ** 2 + (self.y - target.y) ** 2

#g = G*m/dsqd * normalized (self - target)

if dsqd == 0:

return

self.vx += -1 / dsqd * (self.x - target.x) / dsqd ** 0.5

self.vy += -1 / dsqd * (self.y - target.y) / dsqd ** 0.5

def update (self):

self.x += self.vx

self.y += self.vy

pygame.init()

window = pygame.display.set_mode ((600, 400))

main_surface = pygame.Surface ((600, 400))

colours = [0x000000, 0x111111, 0x222222, 0x333333, 0x444444, 0x555555, 0x666666, 0x777777, 0x888888, 0x999999, 0xaaaaaa, 0xbbbbbb] + [0xFF0000, 0x00FF00, 0x0000FF, 0xFFFF00, 0xFF00FF, 0x00FFFF, 0x888888, 0xFFFFFF, 0x808000, 0x008080, 0x800080, 0x800000]

#colours = [0xFF0000, 0x00FF00, 0x0000FF, 0xFFFF00, 0xFF00FF, 0x00FFFF, 0x888888,

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0xFFFFFF, 0x808000, 0x008080, 0x800080, 0x800000] particles = [Particle (200, 100, colours [i]) for i in range (20)] earth = Particle (200, 200)

for i, p in enumerate (particles):

p.vx = i / 100

while (True):

#	main_surface.fill(0x000000)

pygame.draw.circle (main_surface, 0x00FF00, (earth.x, earth.y), 5, 2)

for p in particles:

p.apply_gravity (earth)

p.update ()

pygame.draw.circle (main_surface, p.colour, (int (p.x), int (p.y)), 5, 2)

window.blit(main_surface, (0, 0))

pygame.display.flip()

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Output:

Result:

Thus the Python Program to simulate elliptical orbits using Pygame is executed successfully and the output is verified.

GE8161	

Ex. No. : 13			
			
Date:	SIMULATE BOUNCING BALL USING PYGAME		

Aim:

To write a Python program to bouncing ball in Pygame.

Algorithm:

1.	Import the required packages

2.	Define the required variables

3.	Define the screen space to display the  bouncing balls in that space

Program:
import sys

import pygame

pygame.init()

size = width, height = 320, 240

speed = [2, 2]

black = 0, 0, 0

screen = pygame.display.set_mode(size)

ball = pygame.image.load('C:\\Users\\admin\\Desktop//ball.jpg')

ballrect = ball.get_rect()

while 1:

for event in pygame.event.get():

if event.type == pygame.QUIT: sys.exit()

ballrect = ballrect.move(speed)

if ballrect.left < 0 or ballrect.right > width:

speed[0] = -speed[0]
if ballrect.top < 0 or ballrect.bottom > height:

speed[1] = -speed[1]

screen.fill(black)
screen.blit(ball, ballrect)

pygame.display.flip()

Output:

Result:

Thus the Python Program to simulate bouncing ball using Pygame is executed successfully and the output is verified.

GE8161	

VIVAVOCE QUESTIONS:

1.	What it the syntax of print function?
2.	What is the usage of input function?

3.	Define a variable.
4.	What is type conversion?
5.	Mention the data types in Python
6.	What are the attributes of the complex datatype?

7.	Mention a few escape sequences.
8.	Define an expression
9.	What is the usage of  ** operator in Python?
10.	Give the syntax of  if else statement.

11.	Give the syntax of for statement.
12.	How is range function used in for?

13.	Give the syntax of while statement.
14.	What are multi way if statements?

15.	How is random numbers generated?
16.	Define a function.
17.	Give the syntax of function.
18.	What are the types of arguments in function.?

19.	What is a recursive function?
20.	What are anonymous functions?
21.	What are default arguments?
22.	What are variable length arguments?

23.	What are keyword arguments?
24.	Mention the use of map().

25.	Mention the use of filter().
26.	Mention the use of reduce().

27.	Define a string.
28.	How is string slicing done?
29.	What is the usage of repetition operator?
30.	How is string concatenation done  using + operator>

31.	Mention some string methods
32.	How is length of a string found?
33.	How is a string converted to its upper case?
34.	`Differentiate isalpha() and isdigit().

35.	What is the use of split()?
36.	Define a file.

37.	Give the syntax for opening a file.
38.	Give the syntax for closing a file.

39.	How is reading of file done?
40.	How is writing of file done?
41.	What is a list?
42.	Lists are mutable-Justify.

43.	How is a list created?
44.	How can a list be sorted?
45.	How are elements appended  to the list?
46.	How is insert() used in list?

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47.	What is the usage of pop() in list?

48.	Define a tuple.
49.	Are tuples mutable or immutable?

50.	Mention the use of return statement.
51.	What is a Boolean function?
52.	How is main function defined?
53.	What is a dictionary?

54.	How are tuples created?
55.	How is a dictionary created?
56.	How to print the keys of a dictionary?
57.	How to print the values of a dictionary?

58.	How is del statement used?
59.	Can tuple elements be deleted?

60.	What is Python interpreter?
61.	Why is Python called an interpreted language?

62.	Mention some features of Python
63.	What is Python IDLE?
64.	Mention some rules for naming an identifier in Python.
65.	Give points about Python Numbers.

66.	What is bool datatype?
67.	Give examples of mathematical functions.
68.	What is string formatting operator?
69.	Mention about membership operators inPython.

70.	How is expression evaluated in Python?
71.	What are the loop control statements in Python?

72.	What is the use of break statement?
73.	What is the use of continue statement?

74.	What is the use of pass statement?
75.	What is assert statement?
76.	Differentiate fruitful function s and void functions.
77.	What are required arguments ?

78.	Differentiate pass by value and pass by reference.
79.	Mention few advantages of function.
80.	How is lambda function used?
81.	What is a local variable?

82.	What are global variables?
83.	What are Python decorators?

84.	Are strings mutable or immutable?
85.	What is join()?

86.	What is replace() method?
87.	What is list comprehension?
88.	Define multidimensional list.
89.	How to create lists using range()?

90.	What is swapcase() method?
91.	What is linear search?
92.	How is binary search done?

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93.	How is merge sort performed?

94.	What is sorting?
95.	How is insertion sort done?

96.	How is selection sort done?
97.	What are command line arguments?
98.	Name some built in functions with dictionary.
99.	What is an exception?

100.	How is exception handled in python?