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List Cheat Sheet (DRAFT) by

Introduction to list data structure for group work

This is a draft cheat sheet. It is a work in progress and is not finished yet.

Introd­uction

Lists are used to store multiple items in a single variable and they are created using square brackets:
 
### Example 
my_list = ['Luke', 'San', 'Paras'] 
print(my_list)
Output: ['Luke', 'San', 'Paras']

List Items

List items are ordered, change­able, and allow duplicate values. \ List items are indexed, the first item has index [0], the second item has index [1] etc.
Ordered
When we say that lists are ordered, it means that the items have a defined order, and that order will not change.\ If you add new items to a list, the new items will be placed at the end of the list

Duplicates

Since lists are indexed, lists can have items with the same value:
 
# example 
my_list = ['Luke', 'San', 'San', 'Paras'] 
print(my_list)
Output: ['Luke', 'San', 'San', 'Paras']

Length

To determine number of items a list has, use the len() function:
 
print(­len­(my­_list))
Output: 4
 

The list() Constr­uctor

It is also possible to use the list() constr­uctor when creating a new list.
 
new_list = list((­'Luke', 'San', 'Paras')) 
# note the double round-­bra­ckets 
print(new_list)
Output: ['Luke', 'San', 'Paras']

List Items - Same Data Types

List items can be of any data type:
my_list2 = [0, 1, 3, 5]
my_list3 = [True, False, False, True]
my_list2, my_list3`
Output: ([0, 1, 3, 5], [True, False, False, True])

List Item - Different Data Type

# A list can also contain different data types  
my_list4 = ['Luke', 0, True] 
print(my_list4)
Output: ['Luke', 0, True]

Advantages

• List are mutable, i.e., we can update its data.
• lists keep the order of the elements while dictionary does not. So, it is wise to use a list data structure when you are concerned with the order of the data elements
• Lists are highly useful for array operat­ions.

Disadv­antages

• Lists have the limitation that one can only append at the end
 

Best practices

Always keep in mind that the input to extend must be an iterable object. This could be a set, a tuple, or another list. You will receive an unexpected response if you attempt to pass in something that is not iterable.
it is typically preferable to use the extend method rather than the append method when adding numerous members to a list at once. This is due to the ineffi­ciency of append, which must generate a new list for each element that is added.
Remember that the extend method alters the existing list. You can use the following code to make a new list with the extra elements: my list + new elements = new list