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?
- Most Useful Sequences
- What is list?
- What is list comprehension?
- How to create and take input in list?
- Function provided by list class
- What is str?
- How to create and take input in str?
- Function provided by str class
- What is tuple?
- Difference between tuple and list?
- How to create and take input in tuple?
- Function provided by tuple class
- Build-in Methods for any Sequences
- 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.
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.
There are 3 most useful sequences.
List is the most useful sequence
We will discuss about them one by one. So let start's with list
- List is a sequence
- List stores multiples element in a single variable
- List can contain heterogenous element.
- List is mutable.
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.
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
List are created using square brackets(  ) in the square brackets we write elements separating by commas( , )
As you can see I writes elements separating by commas.
# if the square brackets are empty it will considered as empty list l1= # list() function used to creates list objects l2=list()
# 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 # learn about it l2.append(eval(input()))
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
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)
- 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."
# Empty str s=str()
# by using double quotes " str1="Dev.to" # by using single quotes ' str2='Follow me' # by using """ str3="""Love the post"""
# input() is a function used to take input from user return str str=input("Enter a string")
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.startswith(): check whether the string start with the given text 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
# 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()
- tuple is immutable
- tuple can store heterogenous element
- tuple elements are separated by ','
The most common doubt 👇
Tuple is created using Parenthesis '()' inside it we write element separated by ','
# by using tuple() function which create tuple object t=tuple() # by leaving the parenthesis empty t=()
# 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
tuple class only provide two functions
t.index(): get the index of particular text t.count(): count the occurrence of given text
# 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)
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
# 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)
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.
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This post is created on the request of @meenagupta5
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