baabtra.com little coder chapter - 3

Little Coder Program

by

What you’ve learned?

What is python and why we are using python

How to setup python environment in your or your friends Computer

Python Instruction to print something

How to perform Arithmetic operations using python

What is variables, how can we use variables for better programming?

Printing variables with messages

Strings, Lists, Tuples, and MapsChapter 3

Strings

Strings

• In programming terms, we usually call text as a string. So simply

string is a collection of letters.

• So your name is a string, your address, your email id and you may

find more examples for strings.

Creating strings

• In python we can create strings in three ways

– By enclosing letters in single quotes (‘)

– By enclosing letters in double quotes(“)

– By enclosing letters in 3 single quotes(‘‘‘)

Single quoted strings

>>>myName=‘baabtra.com’

>>>myAge=‘16’

>>>myEmail=‘[email protected]’

>>>myPlace=‘UAE’

Double quoted strings

>>>myName=“baabtra.com”

>>>myAge=“19”

>>>myEmail=“[email protected]”

>>>myPlace=“UAE”

Any difference between single quoted and

double quoted strings?

•



•

No, Literally



• But you should always use the same closing quote with which you

started. For example, below will produce an error

>>>myVar= “Hello ‘

No, Literally

SyntaxError: EOL while scanning string literal



• But you should always use the same closing quote with which you

started. For example, below will produce an error

>>>myVar= “Hello ‘

No, Literally

Problems with single and double quoted strings

Consider the below string

>>> silly_string = ‘He said, "Aren't can't shouldn't wouldn't.“’

Consider the below string

>>> silly_string = ‘He said, "Aren't can't shouldn't wouldn't.“’

SyntaxError: invalid syntax

• In this case, the start of the string is the single quotation mark

before He, and the end of the string, as far as Python is

concerned, is the single quote after the n in Aren, which is not as

we expected. And thus produces an error

How to get rid of this?

How to get rid of this?There are 2 methods

By enclosing in ‘’’ quotes

Or

By using \ operator

By enclosing in ‘’’ quotes

>>> silly_string = ‘’’He said, "Aren't can't shouldn't wouldn't.“’’’

By using / operator

>>> silly_string = ‘He said, "Aren\‘t can\'t shouldn\'t wouldn\'t.“’

ListsLists Are More Powerful than Strings

Lists

• Lists are used when we want to store a list of items in a variable

• Eg: consider if we want to store different fruit names in a variable,

we can make use of lists as below

– Fruit_shop=[‘oranges’, ’apples’, ’bananas’]

Positions of List elements

Consider the below example

Fruit_shop=[‘oranges’, ’apples’, ’bananas’]




Position 0




Position 1




Position 2

Printing lists

>>> fruit_shop=[‘oranges’, ’apples’, ’bananas’]

>>>print(fruit_shop)

Output

[‘oranges’,’apples’,’bananas’]

Printing lists


>>>print(fruit_shop[1])

Output

[’apples’]

Printing lists


>>>print(fruit_shop[2])

Output

[’bananas’]

Printing lists


>>>print(fruit_shop[0:1])

Output

[‘oranges’,’apples’]

Adding items into list

• To add items to a list, we use the append() function. A function is

a chunk of code that tells Python to do something.


>>> fruit_shop.append(‘grapes’)

>>> fruit_shop.append(‘pineapples’)


Adding items into list

• To add items to a list, we use the append() function. A function is

a chunk of code that tells Python to do something.


>>> fruit_shop.append(‘grapes’)

>>> fruit_shop.append(‘pineapples’)


>>[‘oranges’, ’apples’, ’bananas’, ‘grapes’, ‘pineapples’]

Removing Items from a List

• We used del key word to remove an item from a list


>>> del fruit_shop[2]

>>> print(fruit_shop)

>>> [‘oranges’, ’apples’]

Try this !

• Create a list variable to store the subjects you study in your school

• Create a list variable to store your hobbies

• Create a list variable to store your favorite movie names

Try this !

• Create a list variable to store the subjects you study in your school

>>>mySubjects=[‘science’,’maths’,’English’]

• Create a list variable to store your hobbies

>>>myHobbies=[‘reading’,’Listening to music’,’playing’]

• Create a list variable to store your favorite movie names

>>>favMovies=[‘harrypotter’,’spiderman’,’hulk’]

Tuples

Tuples

• A tuple is like a list that uses parentheses, as in this example:

>>> fibs = (0, 1, 1, 2, 3)

>>> print(fibs[3])

2

“The main difference between a tuple and a list is that a tuple

cannot change once you’ve created it.”

Try this !

• Create a tuple to store all the even numbers below 10

• Create a tuple to store all the odd numbers below 10

• Create a tuple to store all the prime numbers below 25

Try this !

• Create a tuple to store all the even numbers below 10

>>>evenNumbers=(0,2,4,6,8)

• Create a tuple to store all the odd numbers below 10

>>>oddNumbers=(1,3,5,7,9)

• Create a tuple to store all the prime numbers below 20

>>>primeNumbers=(1,2,3,5,7,11,13,17,19)

Maps (Dictionaries)

Maps

• In Python, a map (also referred to as a dictionary) is a collection

of things, like lists and tuples. The difference between maps and

lists or tuples is that each item in a map has a key and a

corresponding value.

Favourite_stars= [

‘football’ : ’David Beckam’,

‘cricket’ : ’Sachin Tendulkar’,

‘Athlete’ : ’Usain Bolt’

]

Maps





Favourite_stars= [




]

This is what we call as key

Maps





Favourite_stars= [




]

This is what we call as

Value

Printing, Adding, Removing from Maps

>>>print(Favourite_stars[‘cricket’])

‘Sachin Tendulkar’

>>>favourite_stars[‘Tennis’ : ‘Federar’]

>>>del favourite_stars[‘athletic’]






We can print using the key






Adding element is easy, You can

just give the key and value





>>>del favourite_stars[‘athletic’]Items can be removed using del

keyword

Try this !

• Create a map/dictionary to store 10 English words an their

meanings

Try this !

• Create a map/dictionary to store 10 English words an their

meanings

Eng_words= [

‘debate’ : ’ to engage in argument or discussion’,

‘engage’ : ‘become involved’,

‘weapons’ : ‘any instrument for use in attack ’

]

Exercise !

Exercise !

• Strings

1. Create a string ‘person’ to store the string ‘HarryLime’

2. Make a string to store the below paragraph and fill the blank with

variable ‘person’

“ but I get the impression that really he'd rather not be bothered. Has

never really grown up and perhaps that accounts for the way he

worshipped Lime.' I wrote there that phrase 'in normal circumstances'

because I met him first at _______'s funeral”

Exercise !

• Lists

1. Make a list of your 3 of you favorite hobbies and give the list the

variable name games. Print the variable after creating

2. Now make a list of 5 of your favorite foods and name the variable

foods. Print the variable after creating

3. Add 2 more hobbies to the list ‘games’

4. Remove last two foods from variable ‘foods’

5. Finally, print both variables

Exercise !

• Tuples

1. Make a tuple to store five of your super hero names in it. Name the

variable ‘superHeroes’

2. Try to remove last super hero from the tuple

3. If you get any error for 2nd question note down it, and understand

why it happened

• Dictionaries

1. Create a dictionary to store the details of your family. ‘Key’ must be

the relation and value must be their name

2. Print the dictionary

End of Chapter 3

baabtra.com little coder chapter - 3

Software