Nitin Reddy

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# Learn Python #7 - List operations π‘!

π‘This is a continuation of what we had learnt in our last post. Let us learn more about some other operations that could be performed on the python lists.

πSo today we will be covering the following list of operations:-

• Combining list
• Removing list items
• Clearing out a list
• Counting how many times an item appeared in the list
• Finding a list item's index

### Combining list

In python, combining the two lists is bit easy. Let's learn through an example...

``````list1 = ['Roger', 'Stark', 'Banner'] //List 1
list2 = ['Steve', 'Tony', 'Bruce'] //List 2

list1.extend(list2)
//['Roger', 'Stark', 'Banner', 'Steve', 'Tony', 'Bruce']
``````

In the above example, list1 is extended by including the list items of list2.

### Removing list items

There are different ways in which the item can be removed from the list. Let's look at them one by one

• `remove` method
``````list1 = ['Roger', 'Stark', 'Banner']
list1.remove('Roger')
``````
• `pop` method
``````list1 = ['Roger', 'Stark', 'Banner', 'Steve', 'Tony', 'Bruce']
list1.pop(0) // 'Roger' is removed from the list since the index specified is 0
// Result - ['Stark', 'Banner', 'Steve', 'Tony', 'Bruce']

list1.pop() // 'Bruce' is removed from the list as it was the last item on the list.
// Result - ['Stark', 'Banner', 'Steve', 'Tony']
``````
• `del` keyword
``````list1 =  ['Roger', 'Stark', 'Banner', 'Steve', 'Tony', 'Bruce']
del list1[2]
// Result -  ['Roger', 'Stark', 'Steve', 'Tony', 'Bruce']
``````

### Clearing out the list

In case you want the delete the content of the lists but not the list, you can use the `clear` method on the list.

``````list1 =  ['Roger', 'Stark', 'Banner', 'Steve', 'Tony', 'Bruce']
list1.clear()
// Result - []
``````

Easy peasy isn't it?

### Counting how many times an item appeared in the list

You can also find the number of appearances of a specific item in a list. This can be achieved by using the `count` method on a list that takes an item as an argument.

``````list1 =  ['Roger', 'Stark', 'Banner', 'Roger', 'Tony', 'Bruce']
list1.count('Roger')
// Result - 2
``````

### Finding a list item's index

This operation would be pretty useful when you want to find and replace an item in the list with another item.
To find an index of an item in a list, we use the `index` method.

``````list1 =  ['Roger', 'Stark', 'Banner', 'Roger', 'Tony', 'Bruce']
list1.index('Roger')
``````

The catch here is that this method will return the index of the first instance of an item from the list.

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