In this tutorial, we’ll look at the different Python loops and explore them in detail with examples and techniques. We’ll also answer some of the common loop related examples here.
How to work with loops in Python?
We learned about Python loop before. But Python’s loop is more flexible than that of other language. We can do more interesting things here. Python’s for loop is versatile. We are going to see some examples about this.
Python Loop over a Sequence
This is a very common example of Python for loop. Suppose we have a sequence of items and we need to traverse the sequence one by one. We can use for loop like this:
#initialize a list items = ["apple", 1, 4, "exit", "321"] #for each item in the list traverse the list for item in items: # print the item print (item),
The output of the following code will be
================== RESTART: /home/imtiaz/Desktop/ltech1.py ================== apple 1 4 exit 321 >>>
Python Loop over a Sequence in Reverse Order
You can also print the previous example int reverse order. To do so, you have to use reversed()
function. reversed()
function reverse the order of a sequence. Have a look over the following code.
#initialize a list items = ["apple", 1, 4, "exit", "321"] #for each item in the list traverse the list #before that reverse the order of the list for item in reversed(items): # print the item print (item),
The output will be
================== RESTART: /home/imtiaz/Desktop/ltech2.py ================== 321 exit 4 1 apple >>>
Python Loop over a Sequence in Sorted Order
You can also print the previous example int sorted order. To do so, you have to use sorted()
function. sorted()
function sort the order of a sequence. Have a look over the following code.
#initialize a list items = [7, 1, 4, 9, 3] #for each item in the sorted list, traverse the list for item in sorted(items): # print the item print (item),
The output will be
================== RESTART: /home/imtiaz/Desktop/ltech4.py ================== 1 3 4 7 9 >>>
Enumerate Values and Corresponding Index
You can also enumerate values of a sequence along with their indexes. To do so, you have to use enumerate()
function. The following code will help understand the thing.
#initialize a list items = [7, 1, 4, 9, 3] #for each item in the list traverse the list for index,value in enumerate(items): # print the index along with their value print ("value of "+str(index)+" is = "+str(value))
The output will be
Traversing Two or More Sequences
Using python for loop you can traverse two or more sequences at the same time. For example, in one sequence you have a list of name and in another sequence you have the list of hobbies of the corresponding persons. So you have to print persons’ name along with their hobbies. So the following example will guide you to do this.
names = [ 'Alice', 'Bob', 'Trudy' ] hobbies = [ 'painting', 'singing', 'hacking'] ages = [ 21, 17, 22 ] #combine those list using zip() function for person,age, hobby in zip(names,ages,hobbies): print (person+" is "+str(age)+" years old and his/her hobby is "+hobby)
The output will be
Alice is 21 years old and his/her hobby is painting Bob is 17 years old and his/her hobby is singing Trudy is 22 years old and his/her hobby is hacking >>>
If you practice more, day by day you will learn many Interesting things about python. That’s all about Python loop example. Hope that you understood well. For any query, please comment below.
#HappyCoding
Had to change the below code when trying to print the list of integers as –
for person,age, hobby in zip(names,ages,hobbies):
print(person + ” is \t “,age,” years old and his/her hobby is ” + hobby)
why we use str(index),str(value) to print that values in enumerate
We uses use str(index) because we must convert (index) into a string before we can use the “+” operator to concatenate it to other strings
We uses use str(value) to because we must convert (value) into a string before we can use the “+” operator to concatenate it to other strings — in case (value) is not a string.
Thanks Imtiaz for sharing such a detailed tutorials on Python with examples for each construct. I wanted to learn python for long time and this material helped me a lot in hands on learning with detailed explanation, Hoping to see many more articles in future.