Module III - Day 2

Python Made Easy: Science and Math Edition

Sep-Dec 2025 batch, Vikrant Patil

Date: 8th Feb 2026

Live note are here https://vikrant.dev/python-made-easy-science-math/students-module3-day1.html

Please login to https://traininghub.vikrant.dev and create a notebook with name module3-day2.ipynb

String formating

template = """
Hi {user},
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: {username}
passwd: {passwd}

Thanks and Regards,
Authority
"""

print(template.format(user="Alex", username="alex234", passwd="%#$$90aLex"))


Hi Alex,
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: alex234
passwd: %#$$90aLex

Thanks and Regards,
Authority

%%file users.csv
Alex,alex23,%sdsdAlx,alex@xyz.com
Samiha,samiha24,$3iujhdi,samiha@xyz.com
Poorva,poorvaj23,56jhsdgyu,poorva@xyz.com
vikrant,vikrantp232,kljs89324,vikrant@xyz.com

Overwriting users.csv

import csv

def userdetails(filename):
    with open(filename) as f:
        creader = csv.reader(f)
        return [row for row in creader]

def send_email(email, contents):
    print(f"sending email to {email}")
    print(contents)

def create_email_contents(user, username, passwd):
    return template.format(user=user, username=username, passwd=passwd)

def process_list_send_emails(filename):
    users = userdetails(filename)
    for name, username, passwd in users:
        contents = create_email_contents(name, username, passwd)

userdetails("users.csv")

[['Alex', 'alex23', '%sdsdAlx', 'alex@xyz.com'],
 ['Samiha', 'samiha24', '$3iujhdi', 'samiha@xyz.com'],
 ['Poorva', 'poorvaj23', '56jhsdgyu', 'poorva@xyz.com'],
 ['vikrant', 'vikrantp232', 'kljs89324', 'vikrant@xyz.com']]

ans = 42
f"Answer to question of life is {ans}"

'Answer to question of life is 42'

s = "Answer to question of life is {ans}"

s.format(ans=ans)

'Answer to question of life is 42'

a, b = 10, 20

f"{a} + {b} = {a+b}"

'10 + 20 = 30'

name = "vikrant"

f"{name} is my name!"

'vikrant is my name!'

f"{name} is india's war ship"

"vikrant is india's war ship"

"{name} , how are you?"

'{name} , how are you?'

import csv

def userdetails(filename):
    with open(filename) as f:
        creader = csv.reader(f)
        return [row for row in creader]

def send_email(email, contents):
    print(f"sending email to {email}")
    print(contents)

def create_email_contents(user, username, passwd):
    return template.format(user=user, username=username, passwd=passwd)

def process_list_send_emails(filename):
    users = userdetails(filename)
    for name, username, passwd, email in users:
        contents = create_email_contents(name, username, passwd)
        send_email(email, contents)
        print("x"*30)

process_list_send_emails("users.csv")

sending email to alex@xyz.com

Hi Alex,
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: alex23
passwd: %sdsdAlx

Thanks and Regards,
Authority

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
sending email to samiha@xyz.com

Hi Samiha,
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: samiha24
passwd: $3iujhdi

Thanks and Regards,
Authority

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
sending email to poorva@xyz.com

Hi Poorva,
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: poorvaj23
passwd: 56jhsdgyu

Thanks and Regards,
Authority

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx
sending email to vikrant@xyz.com

Hi vikrant,
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: vikrantp232
passwd: kljs89324

Thanks and Regards,
Authority

xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

'Answer to question of life is {ans}'

s.format(ans=ans)

'Answer to question of life is 42'

template.format

function arguments

def func(a, b):
    return a + b

func(30, 50)

func(a=30, b=50)

func(a=a, b=b) # it will make use of loca variable a and b

template2 = """
Hi {name},
   How are you doing? It is great pleasure to tell you that
your application has been shortlisted for the program.

Please send more details as given below.
...
..

You will get stipend of Rs 10000/- per month during the program
You will need user crendentials on the campus as given below

username: {user}
passwd: {password}

Thanks and Regards,
Authority
"""

def create_email_contents(user, username, passwd):
    return template2.format(name=user, user=username, password=passwd)

name

'vikrant'

name.center(100)

'                                              vikrant                                               '

name.center(10)

' vikrant  '

name.center(20)

'      vikrant       '

name.rjust(20)

'             vikrant'

name.ljust(20)

'vikrant             '

Riffle Shuffle

Remember the card game that we play. We will try to simulate riffle shuffle of a deck

A = ["A1", "A2", "A3", "A4"]
B = [f"B{i}" for i in range(1, 5)]
deck = A + B

deck

['A1', 'A2', 'A3', 'A4', 'B1', 'B2', 'B3', 'B4']

deck[1:]

['A2', 'A3', 'A4', 'B1', 'B2', 'B3', 'B4']

n = len(deck)
mid = n//2 # ineteger
part1 = deck[:mid] # take first half
part2 = deck[mid:] # drop first half

s = []
for x, y in zip(part1, part2):
    s.extend([x,y])
if len(part1) < len(part2):
    s.extend([part[-1]])

['A1', 'B1', 'A2', 'B2', 'A3', 'B3', 'A4', 'B4']

part1

['A1', 'A2', 'A3', 'A4']

part2

['B1', 'B2', 'B3', 'B4']

def riffle_shuffle(deck):
    n = len(deck)
    mid = n//2 # ineteger
    part1 = deck[:mid] # take first half
    part2 = deck[mid:] # drop first half

    s = []
    for x, y in zip(part1, part2):
        s.extend([x,y])
    if len(part1) < len(part2):
        s.extend([part2[-1]])
    return s

riffle_shuffle(deck)

['A1', 'B1', 'A2', 'B2', 'A3', 'B3', 'A4', 'B4']

def sumofsquares(a, b):
    return square(a) + square(b)

def square(x):
    return x*x

def sumof(a, b, func):
    return func(a) + func(b)

sumofsquares(32, 42)

sumof(32, 42, square)

square(32)

def cube(x):
    return x*x*x

sumof(32, 42, cube)

f(x) = x**2 + 2*x + 1
f(f(f(f(f(4))))))

Here we are applying f on 4 five times!

def repeat(func, arg, n):
    """
    applies function func to arg , n times
    """
    for i in range(n):
        arg = func(arg)
        print(f"{i:2d}","".join(arg))
    return arg

repeat(riffle_shuffle, "hello world!", 15)

 0 hweolrllod !
 1 hlwleoodl r!
 2 holdwll ero!
 3 hlo ledrwol!
 4 hdlrow olle!
 5 h dollrloew!
 6 hr ldooelwl!
 7 hore llwdlo!
 8 hlowrdel ol!
 9 hello world!
10 hweolrllod !
11 hlwleoodl r!
12 holdwll ero!
13 hlo ledrwol!
14 hdlrow olle!

['h', 'd', 'l', 'r', 'o', 'w', ' ', 'o', 'l', 'l', 'e', '!']

deck

['A1', 'A2', 'A3', 'A4', 'B1', 'B2', 'B3', 'B4']

repeat(riffle_shuffle, deck, 10)

 0 A1B1A2B2A3B3A4B4
 1 A1A3B1B3A2A4B2B4
 2 A1A2A3A4B1B2B3B4
 3 A1B1A2B2A3B3A4B4
 4 A1A3B1B3A2A4B2B4
 5 A1A2A3A4B1B2B3B4
 6 A1B1A2B2A3B3A4B4
 7 A1A3B1B3A2A4B2B4
 8 A1A2A3A4B1B2B3B4
 9 A1B1A2B2A3B3A4B4

['A1', 'B1', 'A2', 'B2', 'A3', 'B3', 'A4', 'B4']

def repeat_count(func, arg):
    newarg = arg[:]
    count = 1
    newarg = func(newarg)
    while newarg != arg:
        newarg = func(newarg)
        count += 1
    return count

repeat_count(riffle_shuffle, deck)

repeat_count(riffle_shiffle, list("hello world!"))

print("length", "shuffles")
for i in range(1, 53):
    print("{i:6d} {s:8d}".format(i=i, s=repeat_count(riffle_shuffle, list(range(i)))))

length shuffles
     1        1
     2        1
     3        1
     4        2
     5        2
     6        4
     7        4
     8        3
     9        3
    10        6
    11        6
    12       10
    13       10
    14       12
    15       12
    16        4
    17        4
    18        8
    19        8
    20       18
    21       18
    22        6
    23        6
    24       11
    25       11
    26       20
    27       20
    28       18
    29       18
    30       28
    31       28
    32        5
    33        5
    34       10
    35       10
    36       12
    37       12
    38       36
    39       36
    40       12
    41       12
    42       20
    43       20
    44       14
    45       14
    46       12
    47       12
    48       23
    49       23
    50       21
    51       21
    52        8