Module 1 - Day 2

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# Header -> top level header
## Header1 -> second level header
### Header2 -> third level header

Quick recap

• int
• float
• operator-precedence
• text/string (can not be edited once created)
• list - ordered collection of object
• dictinary - it is collection of named values … key:value
• tuple - similar to list but can not be edited once created
• variable/literal
• boolean - True/False
• None

Functions

\(f(x) = x^{2} + 2x + 1\)

numbers = [1, 2, 3, 4, 5, 6, 7, 8]

sentence = "How are you doing today?"

person = {"name": "Vikrant",
          "address": "Maharashtra",
          "company": "Pipal Academy"}

len(numbers) # this will take any collection as argument

8

len(sentence) # it includes every char in the sentence including spaces, new lines , questioon marks etc.

24

len(person) # it will how many pairs?

3

multiline = """This is first line
this second
and this is third one!"""

multiline

'This is first line\nthis second\nand this is thrid one!'

len(multiline)

53

"\n" # new line

'\n'

"\t" # tab

'\t'

"\\" # windows sep

'\\'

len('\\') # this is one char

1

len("\n")

1

len("\\n")

2

print("there is a \t tab")

there is a   tab

print("one\ntwo")

one
two

print(multiline)

This is first line
this second
and this is third one!

multiline

'This is first line\nthis second\nand this is third one!'

2 + 3

5

print(2+3) # print(5)

5

sum(numbers) # the collection that we are passing as an argument to sum should have numeric values in it

36

words = ["one", "two", "three"]

sum(words)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[32], line 1
----> 1 sum(words)

TypeError: unsupported operand type(s) for +: 'int' and 'str'

x,y = 5,10

sum(x, y)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[34], line 1
----> 1 sum(x, y)

TypeError: 'int' object is not iterable

sum([x, y])

15

type(x) # this will tel what is the data type stored in this variable

int

type(numbers)

list

type(person)

dict

type(sentence)

str

type(x)

int

x

5

type(10) # literal

int

strten = "10"

strten

'10'

strten + 1

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[48], line 1
----> 1 strten + 1

TypeError: can only concatenate str (not "int") to str

int(strten) + 1

11

strten

'10'

strten

'10'

1 + strten

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[54], line 1
----> 1 1 + strten

TypeError: unsupported operand type(s) for +: 'int' and 'str'

 min(numbers)

1

max(numbers)

8

sum(person)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[57], line 1
----> 1 sum(person)

TypeError: unsupported operand type(s) for +: 'int' and 'str'

sorted([2, 3, 4, 56, 2, 1, 2, 34])

[1, 2, 2, 2, 3, 4, 34, 56]

unordered_nums = [2, 3, 4, 56, 2, 1, 2, 34]

sorted(unordered_nums) # will return new sorted list

[1, 2, 2, 2, 3, 4, 34, 56]

unordered_nums

[2, 3, 4, 56, 2, 1, 2, 34]

len(numbers)

8

sorted(unordered_nums, reverse=True)

[56, 34, 4, 3, 2, 2, 2, 1]

sorted(unordered_nums, reverse=True) # it is a named argument

[56, 34, 4, 3, 2, 2, 2, 1]

Problem

Use python to find total income if the person has five income sources giving income of 123330, 250000, 45555, 232130, 11123

incomes = [123330, 250000, 45555, 232130, 11123]
sum(incomes)

662138

incomes = [123330, 250000, 45555, 232130, 11123]
total_income = sum(incomes)
print("Total income is:", total_income)

Total income is: 662138

Problem

Find number of digits in \(2^{100}\)

type(1.2)

float

float("34.5")

34.5

type("test")

str

str(35)

'35'

2**100

1267650600228229401496703205376

1200 # this is a number/intger in decimal system that we see... but for a computer it just a number

str(12) # python understands that this number 12 should be converted in to char - digits of decimal format

'12'

value = 2**100 

textvalue = str(value)

textvalue

'1267650600228229401496703205376'

len(textvalue)

31

How to write your own function

countdigits(number)

def countdigits(number): # line should end with colon
    textnumber = str(number)
    count = len(textnumber)
    return count

countdigits(2300)

4

def countdigits_(number): # line should end with colon
    textnumber = str(number)
    count = len(textnumber)
    print(count)

countdigits_(2300)

4

digits = countdigits(2300) # this will store result returned by countdigits into variable digits

4

4

x = 4 # this does not show any interpreter response!

digits

4

digits_ = countdigits_(2300)

4

digits_

print(digits_)

None

countdigits_(2**100)

31

c = countdigits_(2**100)

31

print(c)

None

def say_hello(name):
    print("Hello", name)

say_hello("Arcesium")

Hello Arcesium

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

6546354 + 423423 * add(343, 3434)

1605815025

454 * countdigits(2**100)

14074

454 * countdigits_(2**100)

31

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[103], line 1
----> 1 454 * countdigits_(2**100)

TypeError: unsupported operand type(s) for *: 'int' and 'NoneType'

Example

def twice(x):
    return 2*x

def double(x):
    print(2*x)

twice(twice(10)) # nested calling of a function

40

twice(10)

20

twice(20)

40

twice(twice(10)) # in this inner most function call will be executed first

40

del twice # just like variable you can delete

twice(2)

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
Cell In[120], line 1
----> 1 twice(2)

NameError: name 'twice' is not defined

def twice(x):
    return 2*x

def double(x):
    print(2*x)

twice(twice(twice(20)))

160

double(20)

40

double(double(20))

40

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[125], line 1
----> 1 double(double(20))

Cell In[121], line 5, in double(x)
      4 def double(x):
----> 5     print(2*x)

TypeError: unsupported operand type(s) for *: 'int' and 'NoneType'

def add3(a, b, c): # as many arguments you define here, your function should be called with those many arguments
    return a + b + c

add3(2, 3, 4)

9

add3(2, 3)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[128], line 1
----> 1 add3(2, 3)

TypeError: add3() missing 1 required positional argument: 'c'

add3(2, 3, 4, 5)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[129], line 1
----> 1 add3(2, 3, 4, 5)

TypeError: add3() takes 3 positional arguments but 4 were given

Functions and local variables

def add(x, y): # this x and y is not related to x and y defined above , global space
    return x + y

x

4

y

10

add(10, 20) # after this call is over x and y defined inside function are lost

30

x

4

y

def function(numbers): # when you write the logic of the function assumes the type of argument
    return sum(numbers)

scores = [20, 19, 18, 20, 18]
function(scores)

95

def function2(numbers): # when you write the logic of the function assumes the type of argument
    return sum(numbers), max(numbers)

function2(scores)

(95, 20)

total, max_ = function2(scores)

max = 10 # I lost the connection to original variable where it was pointing

max(scores)

---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
Cell In[149], line 1
----> 1 max(scores)

TypeError: 'int' object is not callable

del max

max(scores)

20

total, max_ = function2(scores)

total

95

max_

20

List of built in functions

• int
• float
• str
• sum
• min
• max
• sorted
• print
• len
• list

list("Python")

['P', 'y', 't', 'h', 'o', 'n']

%load_problem square

Problem: Square

Write a function square to compute the square of a number.

>>> square(4)
16

You can verify your solution using:

%verify_problem square

# your code here
def square(x):
    return x

square(5)

5

%verify_problem square

Found 2 checks
✗ verify square(2)
  expected: 4
  found: 2
✗ verify square(4)
  expected: 16
  found: 4
💥 Oops! Your solution to problem square is incorrect or incomplete.