What is dictionary?
A group of objects are represented as key-value pairs in a data structure is known as dictionary.
Basic Syntax
dic_name = {key : values}
Important points:
- Indexing and slicing not work.
- Insertion order is preserved.
- Heterogenous elements are allowed
- Mutable nature.
- Key must be unique, but duplicates values are allowed.
Access Dictionary:
You can use Python's print() function and the dictionary as an argument to print a dictionary.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
print(dict)
Output is :
{101, 'name': 'Arsalan', 'Field': 'Data Analytics'}
You can also print some specific values from the dictionary by using the key associated with them.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
print(dict[id])
Output is :
Arsalan
An alternative mechanism for getting values out of a dictionary is the get() method. If a key is provided but does not exist a default value is returned instead.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
print(dict.get("name"))
Output is :
Arsalan
Keys Method:
Dictionary objects in python have a built-in method known as keys() function that returns a view object containing the dictionary keys. To get a list of keys in a dictionary use the keys() method.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
print(dict.keys())
Output is :
dict_keys([id, 'name', 'Field'])
Values Method:
In Python, the values() method is a built-in function of dictionary objects that returns a view object that contains the values of the dictionary. The values() process can be used to retrieve a list of values in a dictionary.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
print(dict.values())
Output is :
dict_values([101, 'Arsalan', 'Data Analytics'])
Add Elements:
You can add elements to a dictionary in Python by using the square bracket notation. A key value pairs can be added to a dictionary by simply putting the name of the key within square brackets and giving it a values.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
dict["city"] = "Karachi"
print(dict)
Output is :
{id: 101, 'name': 'Arsalan', 'Field': 'Data Analytics', 'city': 'Karachi'}
Change Elements:
You can change the value of an existing key in a Python dictionary by using the square bracket notation to access the key and then assigning it a new value.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
dict["name"] = "Arsalan Khatri"
print(dict)
Output is :
{id: 101, 'name': 'Arsalan Khatri', 'Field': 'Data Analytics', 'city': 'Karachi'}
Remove Elements:
1). del Method:
To remove a specific key-value pair from a dictionary using the del statement, you can specify the key to be deleted in square brackets.
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
del dict[id]
print(dict)
Output is :
{'name': 'Arsalan', 'Field': 'Data Analytics'}
2). pop() Method:
The pop() method allows you to remove a specific key-value pair from a dictionary by passing the key to be deleted as an argument:
For Example:
dict = {
id : 101,
"name" : "Arsalan",
"field" : "Data Analytics"
}
dict.pop(id)
print(dict)
Output is :
{'name': 'Arsalan', 'Field': 'Data Analytics'}
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