mylist = ["apple", "banana", "cherry"]
List
Lists are used to store multiple items in a single variable.
Lists are one of 4 built-in data types in Python used to store collections of data, the other 3 are Tuple, Set, and Dictionary, all with different qualities and usage.
Lists are created using square brackets:
thislist = ["apple", "banana", "cherry"]
print(thislist)
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.
Changeable
The list is changeable, meaning that we can change, add, and remove items in a list after it has been created.
Allow Duplicates
Since lists are indexed, lists can have items with the same value:
Lists allow duplicate values:
thislist = ["apple", "banana", "cherry", "apple", "cherry"]
print(thislist)
List Length
To determine how many items a list has, use the len() function:
Print the number of items in the list:
thislist = ["apple", "banana", "cherry"]
print(len(thislist))
List Items - Data Types
List items can be of any data type:
String, int and boolean data types:
list1 = ["apple", "banana", "cherry"]
list2 = [1, 5, 7, 9, 3]
list3 = [True, False, False]
A list can contain different data types
A list with strings, integers and boolean values:
list1 = ["abc", 34, True, 40, "male"]
What is the data type of a list?
mylist = ["apple", "banana", "cherry"]
print(type(mylist))
mytuple = ("apple", "banana", "cherry")Tuple
Tuples are used to store multiple items in a single variable.
Tuple is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Set, and Dictionary, all with different qualities and usage.
A tuple is a collection which is ordered and unchangeable.
Tuples are written with round brackets.
ExampleGet your own Python Server
Create a Tuple:
thistuple = ("apple", "banana", "cherry")
print(thistuple)Tuple Items
Tuple items are ordered, unchangeable, and allow duplicate values.
Tuple items are indexed, the first item has index [0], the second item has index [1] etc.
Ordered
When we say that tuples are ordered, it means that the items have a defined order, and that order will not change.
Unchangeable
Tuples are unchangeable, meaning that we cannot change, add or remove items after the tuple has been created.
Allow Duplicates
Since tuples are indexed, they can have items with the same value:
Example
Tuples allow duplicate values:
thistuple = ("apple", "banana", "cherry", "apple", "cherry")
print(thistuple)Tuple Length
To determine how many items a tuple has, use the len() function:
Example
Print the number of items in the tuple:
thistuple = ("apple", "banana", "cherry")
print(len(thistuple))Create Tuple With One Item
To create a tuple with only one item, you have to add a comma after the item, otherwise Python will not recognize it as a tuple.
Example
One item tuple, remember the comma:
thistuple = ("apple",)
print(type(thistuple))
#NOT a tuple
thistuple = ("apple")
print(type(thistuple))Tuple Items - Data Types
Tuple items can be of any data type:
Example
String, int and boolean data types:
tuple1 = ("apple", "banana", "cherry")
tuple2 = (1, 5, 7, 9, 3)
tuple3 = (True, False, False)A tuple can contain different data types:
Example
A tuple with strings, integers and boolean values:
tuple1 = ("abc", 34, True, 40, "male")type()
From Python's perspective, tuples are defined as objects with the data type 'tuple':
<class 'tuple'>Example
What is the data type of a tuple?
mytuple = ("apple", "banana", "cherry")
print(type(mytuple))Python Sets
myset = {"apple", "banana", "cherry"}Set
Sets are used to store multiple items in a single variable.
Set is one of 4 built-in data types in Python used to store collections of data, the other 3 are List, Tuple, and Dictionary, all with different qualities and usage.
A set is a collection which is unordered, unchangeable*, and unindexed.
* Note: Set items are unchangeable, but you can remove items and add new items.
Sets are written with curly brackets.
Note: Sets are unordered, so you cannot be sure in which order the items will appear.
Set Items
Set items are unordered, unchangeable, and do not allow duplicate values.
Unordered
Unordered means that the items in a set do not have a defined order.
Set items can appear in a different order every time you use them, and cannot be referred to by index or key.
Unchangeable
Set items are unchangeable, meaning that we cannot change the items after the set has been created.
Once a set is created, you cannot change its items, but you can remove items and add new items.
Duplicates Not Allowed
Sets cannot have two items with the same value.
Example
Duplicate values will be ignored:
thisset = {"apple", "banana", "cherry", "apple"}
print(thisset)Note: The values True and 1 are considered the same value in sets, and are treated as duplicates:
Example
True and 1 is considered the same value:
thisset = {"apple", "banana", "cherry", True, 1, 2}
print(thisset)Get the Length of a Set
To determine how many items a set has, use the len() function.
Example
Get the number of items in a set:
thisset = {"apple", "banana", "cherry"}
print(len(thisset))Set Items - Data Types
Set items can be of any data type:
Example
String, int and boolean data types:
set1 = {"apple", "banana", "cherry"}
set2 = {1, 5, 7, 9, 3}
set3 = {True, False, False}A set can contain different data types:
Example
A set with strings, integers and boolean values:
set1 = {"abc", 34, True, 40, "male"}type()
From Python's perspective, sets are defined as objects with the data type 'set':
<class 'set'>Example
What is the data type of a set?
myset = {"apple", "banana", "cherry"}
print(type(myset))Python Dictionaries
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}Dictionary
Dictionaries are used to store data values in key:value pairs.
A dictionary is a collection which is ordered*, changeable and do not allow duplicates.
As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.
Dictionaries are written with curly brackets, and have keys and values:
ExampleGet your own Python Server
Create and print a dictionary:
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict)
Dictionary Items
Dictionary items are ordered, changeable, and does not allow duplicates.
Dictionary items are presented in key:value pairs, and can be referred to by using the key name.
Example
Print the "brand" value of the dictionary:
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(thisdict["brand"])
Ordered or Unordered?
As of Python version 3.7, dictionaries are ordered. In Python 3.6 and earlier, dictionaries are unordered.
When we say that dictionaries are ordered, it means that the items have a defined order, and that order will not change.
Unordered means that the items does not have a defined order, you cannot refer to an item by using an index.
Changeable
Dictionaries are changeable, meaning that we can change, add or remove items after the dictionary has been created.
Duplicates Not Allowed
Dictionaries cannot have two items with the same key:
Example
Duplicate values will overwrite existing values:
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964,
"year": 2020
}
print(thisdict)Dictionary Length
To determine how many items a dictionary has, use the len() function:
Example
Print the number of items in the dictionary:
print(len(thisdict))Dictionary Items - Data Types
The values in dictionary items can be of any data type:
Example
String, int, boolean, and list data types:
thisdict = {
"brand": "Ford",
"electric": False,
"year": 1964,
"colors": ["red", "white", "blue"]
}type()
From Python's perspective, dictionaries are defined as objects with the data type 'dict':
<class 'dict'>Example
Print the data type of a dictionary:
thisdict = {
"brand": "Ford",
"model": "Mustang",
"year": 1964
}
print(type(thisdict))
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