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Ujjwal (UG THE SEP)

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# Most Useful Sequences in Python for Beginnersπ¨βπ»

Today in this blog we will learn about the most useful sequences that every Python programmer should know.

Here is the agenda.

## What is Sequence?

• Sequences are a generic term for an ordered set which means that the order in which we input the items will be the same when we access them.
`````` Input: [1,2,3,4,5]
``````

So here if I traverse using loop then it will print the output in the same order as I input data.

• Sequences are iterable but an iterable may not be sequence as set and dict
• Sequence have concept of indexing.

## Most Useful Sequence

There are 3 most useful sequences.

• str
• list
• tuple

List is the most useful sequence
We will discuss about them one by one. So let start's with list

## What is list?

• List is a sequence
• List stores multiples element in a single variable
``````list=[1,'UG-SEP','dev',1.2,(7,'Python')]
``````
• List can contain heterogenous element.
• List is mutable.

## What is list comprehension?

List Comprehension offer a syntax to compress the code it used to take input in list in just one line. It is a very awesome feature to compress code and easy to understand.

### Syntax

``````List= [ expression(element) for element in old List if condition ]
``````

we will learn how to take input from user using List Comprehension in forward topic

## How to create and assign value in list?

List are created using square brackets( [] ) in the square brackets we write elements separating by commas( , )

``````list=['Welcome','Dev','Community']
``````

As you can see I writes elements separating by commas.

### How to create empty list?

``````# if the square brackets are empty it will considered as empty list
l1=[]
# list() function used to creates list objects
l2=list()
``````

### How to take input from user

``````# Using List comprehension
l1=[eval(i) for i in input("Enter data separating by commas").split(',')]

# So in the above line what happen is that first we will enter in
# list comprehension and take input from user after that it will
# be split each element using commas as the criteria the split()
# function split() string on a given criteria and I pass , as the
# criteria so no the each element separated by , are treated as
# list element and now the for run and we evaluate the element and
# assign it.

# using for loop
# create a empty list
l2=list()
# take the size of list
for i in range(0,int(input("Enter the size"))):
# append is a function to add data at the last of the list we will
l2.append(eval(input()))
``````

## Function provided by list class

`````` append() : used to append element at the end of the list
clear()  : to remove all element from the list
copy()   : return shallow copy of the list
count()  : to the number of occurrence of a particular element
index()  : to get the index of a particular element
insert() : to insert element at a particular index
pop()    : to pop a particular element by index no. remove the
last element if index not provided
sort()   : to sort the element in an order
reverse(): to reverse the list
remove() : remove the particular element
``````

Syntax:

``````l=[1,2,3]
# append 4 at the end so l=[1,2,3,4]
l.append(4)
# clear all element l=[]
l.clear()
# shallow copy of l shlcpy=[]
shlcpy=l.copy()
# count the occurrence of 1 but before that let add some value in l
l=[1,2,2,3,1,3,5,7]
print(l.count(1))
# index of a particular element prints the first occurrent index 0
print(l.index(1))
# insert at the 2 and 4th index l=[1,2,2,3,2,1,3,5,7]
l.insert(4,2)
# pop 0 index value l=[2,2,3,2,1,3,5,7]
l.pop(0)
# sort the list l=[1,2,2,2,3,3,5,7]
l.sort()
# reverse the list l=[7,5,3,3,2,2,2,1]
l.reverse()
# sort in descending to ascending
l.sort(reverse=True)
# remove particular element 7 l=[5,3,3,2,2,2,1]
l.remove(1)
``````

## What is str?

• str is a sequence of characters which are iterable
• str is immutable
• str elements are indexed
``````s="Welcome to my blog follow me for more post like this."
``````

## How to create and take input in str?

``````# Empty str
s=str()
``````

### Ways to write str constant

``````# by using double quotes "
str1="Dev.to"
# by using single quotes '
# by using """
str3="""Love the post"""
``````

### How to take input from user in str?

``````# input() is a function used to take input from user return str
str=input("Enter a string")
``````

## Function provided by str class

``````s.replace()   : replace text by another text
s.index()     : get index of a particular text
s.count()     : count the occurrence of a given text
s.split()     : split str on the basis of given criteria returns
list
s.join()      : join each sequence elements separated by the given
criteria
s.endwith()   : check whether the string end with the given text
s.find()      : find some given text in the string
s.upper()     : convert the string to uppercase
s.lower()     : convert the string to lowercase
s.strip()     : remove extra white space from the left and right
of the string
``````

str contain more functions

### Syntax

``````# Let first create a str
s='text'
# let replace 'tex' by 'res' gives 'rest' does not changes in s
# return str object which i have again stored in s so it become
# rest
s=s.replace('tex','res')
# find the index of s which is 2
s.find('s')
# count the occurrence of 'st' which is 1
s.count('st')
# split string on the basis of '' empty space means each char will
# become element of the list l=['r','e','s','t']
l=s.split('')
# join l on the separating by ',' s="r,e,s,t"
s=','.join(l)
# check whether s starts with 'r,e,s' or not True
s.startswith('r,e,s')
# check whether s ends with 's,t' or not True
s.endswith('s,t')
# remove extra white space of '  My  ' using strip s='My'
s='  My  '.strip()
# lowercase the string
s.lowercase()
# uppercase the string
s.uppercase()
``````

## What is tuple?

• tuple is immutable
• tuple can store heterogenous element
• tuple elements are separated by ','
``````t=(1,'Comment','Share',1.5)
``````

The most common doubt π

## How to create and take input in tuple?

Tuple is created using Parenthesis '()' inside it we write element separated by ','

### How to create empty tuple

``````# by using tuple() function which create tuple object
t=tuple()
# by leaving the parenthesis empty
t=()
``````

### How to take input in tuple from user?

``````# using List comprehension we convert the list into tuple using
# tuple() function let check how
t=tuple([eval(i) for i in input("Enter data separated by commas ").split(',')])
``````

You cannot add, modify and delete element in tuple this is a big difference between tuple and list

## Functions provided by tuple class

tuple class only provide two functions

``````t.index(): get the index of particular text
t.count(): count the occurrence of given text
``````

### Syntax

``````# create a tuple
t=(1,2,3,4,'blogging',1)
# get the index of 3 in t which is 2
t.index(3)
# count the occurrence of 1 in t which is 2
t.count(1)
``````

## Build-in Methods for any sequences

``````len(): find the length of a given sequence
min(): finds the min value of the given sequence
max(): finds the min value of the given sequence
sum(): return the sum of the element of given sequence
sorted(): return list after sorting the given sequence
``````

### Syntax

``````# create a sequence
l=[2,5,1,4,3]
# find the len of l which is 5
len(l)
# find the max element which is 5
max(l)
# find the min element which is 1
min(l)
# find the sum which is 15
sum(l)
# sort l but no changes in l return list which is [1,2,3,4,5]
sorted(l)
``````

## Conclusion

This Post will help you to enhance your python skills as a beginner. Don't Forget to Follow me and Give a Unicorn if this post is informative and useful for you.
If you have any doubt then comment below.
This post is created on the request of @meenagupta5
Hope you love itπ

Enter Programmer

Unicornπ¦

Programmer

Thanks a lot @ug π
It is very helpful to me you are really awesome.
You stand on as you said I will post on Monday.
Really to much helpful for me as a beginner...

Ujjwal (UG THE SEP)

My pleasure
Open to help π

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