Python Fundamentals: Strings, Lists, Math, and Plotting Examples

P1: Python String Manipulation Techniques

Demonstrating String Operations

s = "hello"
print(s.capitalize())
print(s.upper())
print(s.rjust(100))
print(s.center(100))
print(s.replace('l','(M)'))
print(s)
print("don't")

Indexing

a = 'symbiosis2024'
print(a[2])

Negative Indexing

print(a[-1])
print(a[-6])

Slicing

print(a[9:12])
print(a[9:])
print(a[9:-1])
print(a[:8])
print(a[-12:-1])

Stride [start index:end index:step size]

print(a[0:13:2])
print(a[0::2])

Concatenation

b = 'hello'
c = 'world'
d = b + c
print(d)
e = b + " " + c
print(e)

Repetition

f = a * 3
print(f)
g = "2024"
print(g * 2)
print(a + '2')

Reversing a String

print(a[::-1])

Split

h = "sspu"
print(h.split()) # Returns a list
i = "05/08/2024"
print(i.split("/"))
j = "14:20:25"
print(j.split(":"))

P2: Essential Python List Operations

Concatenation and Repetition on Lists

L1 = [1, '2', 3.0]
L2 = [4, '5', 6.0]
L3 = L1 + L2 # Concatenation
print(L3)
L4 = L2 + L1
print(L4)
L5 = L1 * 3 # Repetition
print(L5)

Modifying Lists (Append, Insert, Pop, Remove, Del)

lis = [1, 4, 3, 2, 5]
lis.append('sspu')
print(lis)
lis.insert(2, 'hello')
print(lis)
lis.pop()
print(lis)
lis.remove(3)
print(lis)
del(lis[3])
print(lis)

Indexing

l1 = [1, 2, 3, 5, 4, 6, 7, 8]
print(l1[0])
print(l1[5])
print(l1[-1])
print(l1[-3])

Slicing

print(l1[3:6])
print(l1[3:])
print(l1[:6])
print(l1[:])

Stride

print(l1[0:7:2])
print(l1[0:7:3])
print(l1[::2])
print(l1[::3])

Membership Testing: 'in' and 'not in'

lis2 = [1, 4, 3, 2, 5]
if 4 in lis2:
    print("List has element 4")
else:
    print("List does not have element 4")
if 6 not in lis2:
    print("List does not have element 6")
else:
    print('List has element 6')

P3: Advanced String Programming Examples

Program to Reverse a Given String

Using a loop:

s = input("Enter some string:")
i = len(s) - 1
target = ''
while i >= 0:
    target = target + s[i]
    i = i - 1
print(target)

Using slicing (Pythonic way):

print(s[::-1]) # Using stride

Reverse Internal Contents of Each Word in a Sentence

s2 = input("Enter some string:")
l = s2.split()
li = []
i = 0
while i < len(l):
    li.append(l[i][::-1])
    i = i + 1
output = ' '.join(li)
print(output)

Check if a String is a Palindrome

s3 = input("Enter some string:")
s3 = s3.replace(" ", "").lower()
i = 0
length = len(s3) - 1
is_palindrome = True
while i < length:
    if(s3[i] != s3[length]):
        is_palindrome = False
        break
    i += 1
    length -= 1
if (is_palindrome):
    print("The string is palindrome")
else:
    print("The string is not palindrome")

P4: Number Theory: Prime Numbers and Factors

Check Whether a Number is Prime or Composite

num = int(input("Enter a number:"))
i = 2
is_prime = True

if num == 1:
    print("Neither prime nor composite")
elif num > 1:
    while (i < num):
        if(num % i == 0):
            is_prime = False
            break
        i += 1
    if(is_prime):
        print("The number is prime")
    else:
        print("The number is composite")

Find Factors of a Number and Display Their Count

num3 = int(input("Enter a number:"))
k = 1
factors = 0
print("Factors of", num3, ":")
while (k <= num3):
    if(num3 % k == 0):
        print(k)
        factors += 1
    k += 1
print("The number of factors are:", factors)

Find All Two-Digit Prime Numbers and Display Count

num2 = 10
primes = 0
while (num2 < 100):
    is_prime2 = True
    j = 2
    while (j < num2):
        if (num2 % j == 0):
            is_prime2 = False
            break
        j += 1
    if (is_prime2):
        primes += 1
    num2 += 1
print("Total two-digit primes:", primes)

P5: Calculating HCF (GCD) and LCM

Find Highest Common Factor (HCF)

def find_hcf(x, y):
    hcf = 1 # Initialize HCF to 1
    for i in range(1, min(x, y) + 1):
        if ((x % i == 0) and (y % i == 0)):
            hcf = i
    return hcf

num1 = int(input("Enter the first number: "))
num2 = int(input("Enter the second number: "))
hcf_result = find_hcf(num1, num2)
print("The highest common factor of the entered numbers is", hcf_result)

Find Least Common Multiple (LCM)

def find_lcm(a, b):
    max_num = max(a, b)
    while True:
        if max_num % a == 0 and max_num % b == 0:
            return max_num
        max_num += 1

num3 = int(input("Enter a number: "))
num4 = int(input("Enter another number: "))
print("The L.C.M of", num3, "and", num4, "is", find_lcm(num3, num4))

P6: Number Reversal and Palindrome Check

Reversing an Integer

num = int(input("Enter a number: "))
def reversing_number(x):
    reversed_num = 0
    temp_x = x
    while temp_x != 0:
        digit = temp_x % 10
        reversed_num = reversed_num * 10 + digit
        temp_x = temp_x // 10
    return(reversed_num)

print("The reversed number is", reversing_number(num))

Checking if a Number is a Palindrome

def palindrome_number(x, y):
    if x == y:
        print("The entered number is a palindrome.")
    else:
        print("The entered number is not a palindrome.")

palindrome_number(num, reversing_number(num))

P7: Data Visualization using Matplotlib and NumPy

Plotting Sine, Cosine, and Linear Functions

import matplotlib.pyplot as plt
import numpy as np

x = np.arange(0, 10, 0.01)

plt.subplot(3, 3, 1)
plt.plot(x, np.sin(x), color='orange', linewidth = 3, marker = '.', markersize = 1, linestyle = "-")
plt.xlabel("Angle")
plt.ylabel("Magnitude")
plt.title("Sine Wave")

plt.subplot(3, 3, 3)
plt.plot(x, np.cos(x), color="blue", linewidth = 3, marker = ",", markersize = 1, linestyle = "--")
plt.xlabel("Angle")
plt.ylabel("Magnitude")
plt.title("Cosine Wave")

plt.subplot(3, 3, 7)
plt.plot(x, x, color = "red", linewidth = 2, marker = "o", markersize = 1, linestyle = "-.")
plt.xlabel("Values of x")
plt.ylabel("Values of y")
plt.title("Line: y=x")

plt.subplot(3, 3, 9)
plt.plot(x, 5 - x, color="purple", linewidth = 1, marker = "1", markersize = 1, linestyle = ":")
plt.xlabel("Values of x")
plt.ylabel("Values of y")
plt.title("Line: y=5-x")

plt.show()