sequences in python

Storing values in order and again accessing those values using indexes.

In an order arrange the elements and access that through indexes

Three types of sequences:

1. Lists
2. Tuples
3. Strings

Strings : collection/group of characters.

How to create a string ?

Strings can be used using single quotes and double quotes.

reason may be there is no datatype called character.

Python is a case-sensitive language.

How to update a value of a string ? ( background operation )

intially  => s  = "kaushik"

( what happeneds in the background, In your memory a block is created and the value is stored in that block).

this will create a memory location address, this address is assigned to s

Initially,
  s   ------>    0xc123

 but now, the  s= "surya"

the string is created and new memory block is created,

s  ------->  1xzn4

This kind of datatypes are called immutable 

immutable means  ( we cannot changes the values ).

How to clear the contents of a string ?

By simply assigning empty string 

s = "";

How to remove the string ?

if you dont use that string, automatically the reference account is equal to zero.

or

if you want to remove  it manually.

del s;

How to access the content of a string ?

s = "my name is kaushik"

s[0] ------> 1st character

s[0:5] ------> this is the range  ( return those character ).

[ it returns the substring b/w 0 index to 4 ].

s[5:]  ------>    returns all characters starting from index 5.

s[:10]  ------> returns all characters starting from index 0 to 9


String indexing 

1. Positive indexing      (  0 1 2 3 )
( starts from starting character )

2. Negative indexing    (  -4  -3  -2  -1  )
(starts from right most ending ).


How to find out a length of a string ?


S = "Hello How are you"

length   -------->  len(s)

len is a function

max(s)   -------> according to the  ASCII key numbers if you take.

( which is the bigger number from  "s" is  y )

min(s)   --------->   ' '  ( space has minimum value ).


Built-in functions 

string.capitalize    ---->   it will help you to convert the first letter to capital letter.

s='abcd'

List  ( is one of the sequence ).

represents using  []  

[  it stores set of objects  ]

s = [ 1, 2, 3.5 , "hello", "kaushik" ]

( it can store different kinds of objects ).

[ but string only stores characters and is immutable ].

but  in list, you can add or remove the objects at anytime.

add , remove 

create a list,

s = [ 1,2,3,4,5, "TWG" ]

list lo one more sublist 

How to retrieve the elements from the list ?

by using index 

s[0]  --------------->    index 

s[0:3]   ------------->   range index 

How to update the elements from the list ?

s[1] = 10 

Remove an element from the list 

How to remove the list ?

Operators in list 

Example :

Example01:

Membership operator :

in

not in 

In a list, whether the element exists or not.

it will help you to check.

Concatenation operator 

two lists, how you can concatenate ( by using  (+) operator ).

Repetition operator 

*   ------> star 

Append 

count 

index 

Example 

Insert :

reverse:

Tuples 

Tuples :

tuple is also something similar to list 

()   -----> represents 

also known as Read Only List 

once you create the tuple whatever the elements you cannot update them.

you will try to retrieve similarly like list.

you cannot update/modify the tuples.

How to get the length ?