Python Dictionary Append: How to Add Key/Value Pair
The dictionary data type is one of the most important data types that can be used in Python. A dictionary stores information as a key/value pair, with each key representing a different value. Each line is separated by a colon (:), and each key/value pair is separated by a comma (,). (,).
The keys in a dictionary are all unique and can be any type of data, including strings, integers, tuples, and so on. The values can be a list or a list within a list, numbers, strings, or any combination of these.
Here’s an illustration of what a dictionary looks like:
Restrictions on Key Dictionaries
the following values are in my dict: “a”: A, “b”: B, “c”: C, “d”: D
Restriction on the Use of Important Dictionaries
Here is a list of restrictions that can be placed on a key within a dictionary:
Any key that appears twice in a dictionary is treated as the last one defined in the dictionary. Think about the following dictionary definition: my dict = “Name “:”ABC”,”Address “:”Mumbai”,”Age”:30, “Name”: “XYZ”; This key “Name” is defined twice, with the values ABC and XYZ respectively. This will be given to the most recently defined, for example, “Name,” “XYZ,” and so on.
It is possible to have a number, string, float, boolean, tuples, or built-in objects such as classes and functions as the data type for your key value.
For example, my dict = bin:”001′′, hex:”6′′, 10:”ten”, bool:”1′′, float:”12.8′′, int:1, False:’0′; my dict = bin:”001′′, hex:”6′′, 10:”ten”, bool:”1′′, float:”12.8′′, int:1;
You cannot define a key in square brackets, which is the only thing that is not permitted. my dict = [“Name”]: “ABC”, [“Address”]: “Mumbai”, and age: 30; for example
How to append an element to a key in a dictionary with Python?
In Python, how do you append an element to a key in a dictionary that already exists?
To add elements to the keys in the dictionary, we can make use of the built-in function append(), which is available in most programming languages. To add an element to the dictionary using the append() function, we must first identify the key to which the element should be appended.
Assume you have the following dictionary in your possession:
‘my dict’ contains the keys ‘Name”:[],”Address”:[],”Age”:[]; The keys in the dictionary are ‘Name’, ‘Address’, and ‘Age’. With the help of the append() method, we can make changes to the values associated with the keys in the dictionary
my dict = “Name”:[],”Address”:[],”Age”:[]; my dict = “Name”:[],”Address”:[],”Age”:[];
my dict[“Name”].
append(“Guru”)
my dict[“Address”].
append(“Mumbai”)
my dict[“Age”].
append(30)
print(my dict)
This is the output we get when printing the dictionary after it has been updated with the new values:
Output:
‘Name’: [‘Guru,’] ‘Address’: [‘Mumbai,’], ‘Age’: [30] ‘Name’: [‘Guru,’ Address’: [‘Mumbai,’ Age’: [30]
Obtaining information from the elements of a dictionary
The information contained within a dictionary is accessible as a key/value pair. It is necessary to use square brackets ([‘key’]) with the key inside them in order to access the elements from a dictionary.
As an illustration, consider the following code, which demonstrates how to access elements from a dictionary by using the key in the square bracket.
In my dict, “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai” are all values.
The following are the outputs: print(“username:”, my dict[‘username’]) print(“email:”, my dict[’email’]) print(“location:”, my dict[‘location’]) print(“username:”, my dict[‘username’])
Accessing elements of a dictionary
XYZ is a username; xyz@gmail.com is an email address.
Mumbai is the location.
If you attempt to use a key that does not exist in the dictionary, you will receive the following error:
In my dict, “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai” are all values.
print(“name:”, my dict[‘name’]) is equivalent to print(“name:”).
Output:
Traceback (from the most recent call to the most recent call):
Line 2 of file “display.py” in module “display.py”
print(“name:”, my dict[‘name’]) is equivalent to print(“name:”).
‘name’ was entered incorrectly as a key error.
Delete one or more elements from a dictionary
It is necessary to make use of the del keyword in order to remove an element from a dictionary.
The syntax is as follows:
del dict[‘yourkey’] # Delete the key. This will eliminate the element associated with your key.
You can make use of the del keyword once more to delete the entire dictionary, as shown in the example below:
del my dict # this will remove the dictionary with the name my dict from the system.
You can use the clear() method on your dictionary to simply empty the dictionary or clear the contents contained within the dictionary, as shown in the example below:
Deleting element(s) in a dictionary
your dict.clear()
Here is a working example that demonstrates how to delete an element, how to clear the contents of a dictionary, and how to delete the entire dictionary.
In my dict, “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai” are all values.
the value of my dict[‘username’] del # it will remove the string “username”: “XYZ” from my dict print(my dict) my dict.clear() # it will make the dictionarymy dictempty print(my dict) delmy dict # it will delete the dictionarymy dict print(my dict) my dict.clear() # it will make the dictionarymy dictempty print(my dict) delmy dict # it will delete the dictionarymy dict print(my dict
Output:
email address: xyz@gmail.com; location: Mumbai; email address: xyz@gmail.com;
{}
Traceback (from the most recent call to the most recent call):
Line 7 of file “main.py” in the module> section.
print(my dict)
NameError: The name’my dict’ does not exist in the dictionary.
Using the pop() method, you can remove element(s) from a dictionary.
In addition to the del keyword, you can also remove an element from the dictionary by calling the dict.pop() method on the element in question. The pop() method is a built-in method that comes with a dictionary and is used to delete an element based on the key that is provided.
Syntax:
dict.pop is a text-to-speech programme (key, defaultvalue)
It is returned by the pop() method when an element has been removed for the specified key, and if the specified key is not present, the defaultvalue is returned. If the defaultvalue is not specified and the key is not found in the dictionary, the programme will return an error message.
Deleting Element(s) from dictionary using pop() method
Here is a working example that demonstrates how to delete an element using the dict.pop() function.
In my dict, “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai” are all values.
my dict.pop(“username”) \sprint(my dict) \sOutput:
email address: xyz@gmail.com; location: Mumbai; email address: xyz@gmail.com;
Adding an element or elements to a dictionary
To add an element to an existing dictionary, you must first use the dictionary name followed by square brackets with the key name and then assign a value to the key name in the square brackets.
Here’s an illustration of what I’m talking about:
In my dict, “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai” are all values.
my dict[‘name’]=’Nick’
print(my dict) \sOutput:
‘XYZ’ is the username, ‘xyz@gmail.com’ is the email address, ‘Mumbai’ is the location, and ‘Nick’ is the name.
Existing elements in a dictionary are being updated.
To make changes to existing elements within a dictionary, you must first obtain a reference to the key for which the value is to be changed.
Appending element(s) to a dictionary
As a result, we have a dictionary my dict where “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai.”
Please change the username from XYZ to ABC if you are willing to. Here’s an example of how you can make changes to your document.
In my dict, “username” is “XYZ,” “email” is “xyz@gmail.com,” and “location” is “Mumbai” are all values.
“ABC” is the value of my dict[“username”].
print(my dict) \sOutput:
‘ABC’ is the username, ‘xyz@gmail.com’ is the email address, and ‘Mumbai’ is the location.
Inserting a dictionary into another dictionary is called insertion.
Assume you have two dictionaries, one of which is shown below:
Dictionary number one:
my dict = “username”: “XYZ,” “email”: “xyz@gmail.com,” “location”: “Washington” Dictionary 2: “username”: “XYZ,” “email”: “xyz@gmail.com,” “location”: “Washington”
Updating existing element(s) in a dictionary
the value of my dict1 is “firstName”: “Nick”, and the value of my dict2 is “lastName”: “Price”
In order to accomplish this, I would like my dict1 dictionary to be inserted into my dict dictionary. Make a key called “name” in my dict and assign it to the dictionary my dict1 in order to accomplish this goal.
An example of inserting a dictionary into another dictionary is shown in the following working example.
the variables my dict and xyz are defined as follows: “username”: “XYZ,” “email”: “xyz@gmail.com,” and “location”: “Washington.”
the value of my dict1 is “firstName”: “Nick”, and the value of my dict2 is “lastName”: “Price”
[“name”] = my dict1 + my dict2
print(my dict) \sOutput:
Summary:
‘XYZ’ is the username, ‘xyz@gmail.com’ is the email address, ‘Mumbai’ is the location, and ‘name’ is ‘firstName’ is ‘Nick’ and ‘lastName’ is ‘Price’.
Now, if you look at the key “name,” you will notice that it has the dictionary my dict1.
Summary: The dictionary data type in Python is one of the most important data types available. A dictionary stores information as a key/value pair, with each key representing a different value. There is a colon (:) between the key and the value, and a comma (,) between the key and value pair (,). The keys in a dictionary are all unique and can be any type of data, including strings, integers, tuples, and so on. The values can be a list or a list within a list, numbers, strings, or any combination of these.
| Method | Description |
|---|---|
| clear() | It will remove all the elements from the dictionary. |
| append() | It is a built-in function in Python that helps to update the values for the keys in the dictionary. |
| update() | The update() method will help us to merge one dictionary with another. |
| pop() | Removes the element from the dictionary. |