Python has 4 built Data structures that dictate how data is stored, accessed and accessed.
1. Sets
2. Dictionaries
3. Tuples
4. Lists
Characteristics of List
1. Stored in square brackets [ ]
2. Ordered
3. Mutable
4. Can hold duplicate values
How to Access and Read Lists
Index
Lists can be accessed through index( 0 as the beginning index on the furthest left and -1 when starting from the last element )
Slicing
In slicing we aim to use indexing to extract a part of our list, but a key part to be know is that the end isn't included in our sub_list
Code : my_list [start: stop: step]
How to Unpack
Unpacking is taking all the items in a list and assigning variables in order to perform operations.
In places where you don't want to assign a variable you use an underscore
How to explore and analyze
To explore the the highest, lowest, how big our list is
len(my_list): Returns the total number of elements in the list.
max(my_list): Finds the highest value (numeric or alphabetical).
min(my_list): Finds the lowest value.
sum(my_list): Calculates the total sum of all numeric values
How to search for specific items and count how often they appear
my_list.count(x): Counts how many times the value x appears.
my_list.index(x): Finds the index position of the first occurrence of x
How to check membership and identity
x in my_list
x is my_list
How to check quality of our list
all(my_list): Find all values with real meaning, if we have missing values the feedback will be false
any(my_list): Have at least 1 value, you only get a false if all items are missing .
How to change
Append
Appends adds new data at the end of the list
my_list.append(value)
Insert
Insert adds specific values at specific position
my_list.insert(index, value)
Clear
Deletes all the items in the list
my_list.clear()
Remove by value
This removes the first items of that value
my_list.remove(value)
Deleting by position (pop)
This you need to specify the index position of item you want to delete and it returns what has been removed. You need to specify the index in order to avoid deleting all information on the list
my_list.pop(index)
Update
In this case we use indexing and the = sign , if you don't specify the index you will end up updating the whole list
my_list[index] = new_value
How to order a list in python
Sort
We can change the order of the original list using sort()
my_list.sort() will order the original list in an ascending order
my_list.sort(reverse=True) will sort the original list in a descending order
Sorted
This method , leaves the original list creates a new one copy and changes the order
new_list = sorted(my_list) creates a copy and sorts in an ascending order
new_list_desc = sorted(my_list, reverse=True) creates a copy and sorts in a descending order
Reverse
No sorting logic is involved here, it just reverses the structure of the list(last to first)
This changes the original list
my_list = ["A", "B", "C", "D"]
Reverse - changes the original list : my_list.reverse()
print(my_list) : ['D', 'C', 'B', 'A']
Reversed
This creates a copy and reverses it
my_list = ["A", "B", "C", "D"]
new_list = list(reversed(my_list))
print(new_list) : ['D', 'C', 'B', 'A']
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