# Iterations

In this tutorial, we shall discuss the Iterations. Topics we covered in the last tutorial:

• Boolean
• Comparison  Operators
• Decision Making in Python:

## Iterations:

In normal execution, each statement is executed only once, but in iterations, the output is displayed continuously until the given condition breaks.

Types of iterations in python:

• For
• While

### For loop example:

Executes a sentence multiple times. If we want to print all the elements of a list it takes a lot of time to do that. Let us see those in the code.

Here ‘num’ is a  variable that we are declaring and say to python that this ‘num’ is an element is a list.

## While:

This loop statement checks the condition initially and then continues.

## Range:

To create a sequence of a very large number of elements becomes difficult many times, so the range is something by using we can create longer numeric sequences.

Let us create a list in Jupyter notebook.

## List comprehension:

When we assign the elements of the first list to the second list in a modified way of elements, They are two ways of doing such things

• Normal looping.
• List comprehension.

## Normal Looping:

X = [ 1, 2 ,3 ,4 ,5 ,6 ]                   # first list whose items should be assigned

Y = [ ]                                              # empty list , where items should be assigned.

for num in X:

Y.append(num**2)

Y= [ 1, 4 ,9 ,16 , 25 , 36 ] # output of the iteration

## List comprehension:

Y= [ num**2 for num in X ]        # List comprehension method for same action.

Topics we will cover in the next tutorial:

• Function
• Map and filter
• lambda
• Tuple unpacking