A list is a collection which is ordered and changeable. In Python lists are written with square brackets.
Use the code below to create & print a list
mycolors= [“red”, “blue”, “green”]
print(mycolors)
You access the list items by referring to the index number, index start from 0, in case you want to access/print the
last item from the list “mycolors” above you can use the code
print( mycolors[2] )
You can even use the Negative indexing means beginning from the end, -1
refers to the last item, -2
refers to the second last item etc. You can print last item in the list using the code print( mycolors[-1] )
You can also specify a range of indexes by specifying where to start and where to end the range.
thislist = [“apple”, “banana”, “cherry”, “orange”, “kiwi”, “melon”, “mango”]
print(thislist[2:5])
The code above will Return the third, fourth, and fifth item
Note: The search will start at index 2 (included) and end at index 5 (not included).
We can use the code below to change the value of any item in the list :
mycolors= [“red”, “blue”, “green”]
mycolors[1] = “black”
Check list length
mycolors= [“red”, “blue”, “green”]
print(len(mycolors))
Check if Item Exists
To determine if a specified item is present in a list use the in
keyword:
mycolors= [“red”, “blue”, “green”]
if “blue” in mycolors:
print(“Yes, ‘blue’ is in the mycolors list”)
Add Items
To add an item to the end of the list, use the append() method:
mycolors= [“red”, “blue”, “green”]
mycolors.append(“orange”)
print(mycolors)
To add an item at the specified index, use the insert() method
Insert an item as the second position:
mycolors= [“red”, “blue”, “green”]
mycolors.insert(1,“orange”)
print(mycolors)
Remove Item
There are several methods to remove items from a list
The remove()
method removes the specified item:
mycolors= [“red”, “blue”, “green”]
mycolors.remove(“blue”)
print(mycolors)
The pop()
method removes the specified index, (or the last item if index is not specified):
mycolors= [“red”, “blue”, “green”]
mycolors.pop()
print(mycolors)
The del
keyword removes the specified index:
mycolors= [“red”, “blue”, “green”]
del mycolors[0]
print(mycolors)
The del
keyword can also delete the list completely:
mycolors= [“red”, “blue”, “green”]
del mycolors
The clear()
method empties the list:
mycolors= [“red”, “blue”, “green”]
mycolors.clear()
print(mycolors)
Make a copy of a list with the copy()
method:
mycolors= [“red”, “blue”, “green”]
mylist = mycolors.copy()
print(mylist)
Make a copy of a list with the list()
method:
mycolors= [“red”, “blue”, “green”]
mylist = list(mycolors)
print(mylist)
How to Print all items in the list using loop :
mycolors= [“red”, “blue”, “green”]
for x in mycolors:
print(x)
List Methods
Python has a set of built-in methods that you can use on lists.
Method | Description |
---|---|
append() | Adds an element at the end of the list |
clear() | Removes all the elements from the list |
copy() | Returns a copy of the list |
count() | Returns the number of elements with the specified value |
extend() | Add the elements of a list (or any iterable), to the end of the current list |
index() | Returns the index of the first element with the specified value |
insert() | Adds an element at the specified position |
pop() | Removes the element at the specified position |
remove() | Removes the item with the specified value |
reverse() | Reverses the order of the list |
sort() | Sorts the list |
You can find more Python Tutorials on https://www.w3schools.com/python
Comment here