Python List

The Python Collections / Arrays

In this tutorial, we will be learning a few python list functions. In the Python programming language, there are basically four different collection data types. And those four different collection data types are mentioned below.

• List

This collection data type has a collection which can be ordered or changeable. This collection data type can further include duplicate members.

• Tuple

This collection data type has a collection that is ordered and unchangeable. This collection data type can also include duplicate members.

• Set

This collection data type has a collection which is basically unordered and unindexed. This collection data type does not allow duplicate members.

• Dictionary

This collection data type has a collection that is unordered, indexed, and changeable. This collection data type also does not allows duplicate members. As a developer, before you go ahead and choose any particular kind of collection type it is important for you to first understand all the properties or know all kinds of information about the different kinds of collection types. This will allow you to make a better-informed decision. We will be discussing all the list functions with the help of some Python list exercises. You should also remember that when you choose the right type of collection type for a particular set of data then that could mean that either the meaning of the data must be retained or there must be an in the overall efficiency or security.

The List

As we mentioned above, in this programming language a list is a collection type that is changeable and ordered. It is also important for you to know that when you need to use the function of lists then you need to write it in square brackets. For example, if you want to create a list then

thislist = [“apple”, “banana”, “cherry”]

print(thislist)

To Access Items

As a developer if you need to access any of the list items from the entire Python list length then you can do that by referring to the index number of that particular list item. For example, if you need to print the second the second item of the list then

thislist = [“apple”, “banana”, “cheery”]

print (thislist [1] )

To Change Item Value

If you wish to change the item value for any specific type of item from the entire Python list length then for this you will also be required to refer to the index number of that particular item. For example, if you wish to change the value of the second item then

thislist = [“apple”, “banana”, “cheery”]

thislist [1] = “blackcurrant”

print (thislist)

To Loop Through a List

While using this programming language if you wish to loop through the list items then it is recommended that you should use the function of for loop. For example, if you wish to print all the items that are present in the one by one then

thislist = [“apple”, “banana”, “cherry”]

for x in thislist:

print (x)

However, this is not it in this Python tutorial on one of the Python list functions of for. We will be taking up this topic again in the Python Loops section of this Python tutorial.  

The List Length

If you wish to find out about the number of items that are present in any particular list then for that you would have to use the len( )method. For example, if you need to print the number of items that are present in a list then

thislist = [“apple”, “banana”, “cherry”]

print  (len(thislist) )

To Add Items

If you wish to add any particular item at the end of the Python list length then for that you need to use the append( ) method. For example

thislist = [“apple”, “banana”, “cherry”]

thislist . append (“orange”)

print (thislist)

If you further wish to add any particular item at the specified index then for that you would have to use the insert ( ) method. For example, if you wish to add any particular item in the second position then

thislist = [“apple”, “banana”, “cherry”]

thislist . insert (1, “orange”)

print (thislist)

To Remove an Item

As a developer who is using this programming language, if you ever wish to remove any particular item for the list then there are a number of different methods that you can practice or try out to test the function of Python list remove. Some of those methods through which you can remove any particular list item from the list are mentioned below.

• The remove ( ) method

This method helps in removing one specific item from the entire list. For example

thislist = [“apple”, “banana”, “cherry”]

thislist . remove (“banana”)

print (thislist)

• The pop ( ) method

The Python list pop method helps in removing the specified item from the list and if one fails to specify the item that needs to be removed from the list then the last item is by default removed from the entire list. For example

thislist = [“apple”, “banana”, “cherry”]

thislist . pop ( )

print (thislist)

• The del keyword method

The Python list del method helps in removing the specified item from the list. For example

thislist = [“apple”, “banana”, “cherry”]

thislist . pop ( )

print (thislist)

It is important for you to remember that you can also use this method to remove the list completely. For example

thislist = [“apple”, “banana”, “cherry”]

del thislist

print (thislist) #this will cause an error because “thislist” no longer exists.

With the help of this method, you can choose to empty the list. For example

thislist = [“apple”, “banana”, “cherry”]

thislist . clear ( )

print (thislist)

The List Constructor

If you instead want to make or construct the list then you need to use the list ( ) constructor method which is one of the Python list functions. For example

thislist = list ( (“apple”, “banana”, “cherry”) ) # note the double round brackets

print (thislist)

The List Methods When it comes to using a number of different methods on the list then it is important for you to know that this Python programming language comes with a few built-in methods. And some of those built-in methods that you can use on any list are mentioned below.

  With this, we finish the Python list functions part of our Python tutorial.