Easy methods to Add Key/Worth Pair

Python dictionary is a group sort that shops information in key-value pairs. It’s unordered, changeable, and doesn’t permit duplicates. Dictionaries are very environment friendly for trying up and inserting information, as they use a method known as hashing to map keys to their related values. They’re a strong information construction that permits you to retailer and manipulate information in a key-value pair format. One frequent activity when working with dictionaries is to append new values to an current dictionary. Whereas Python dictionaries shouldn’t have an append() technique like lists do, a number of methods exist so as to add new key-value pairs to a dictionary. On this weblog submit, we’ll discover a few of these strategies and talk about when to make use of each. So, let’s dive in!

Dictionary in Python

A dictionary is a crucial information sort in Python programming. It’s a assortment of knowledge values which can be unordered. Python dictionary is used to retailer gadgets wherein every merchandise has a key-value pair. The dictionary is made up of those key-value pairs, and this makes the dictionary extra optimized. 

For instance –

Dict = {1: 'Studying', 2: 'For', 3: 'Life'}
print(Dict)

Right here, 

The colon is used to pair keys with the values.

The comma is used as a separator for the weather. 

The output is:

{1: ‘Learnings’, 2: ‘For’, 3: ‘Life’}

Python dictionary append is just used so as to add key/worth to the present dictionary. The dictionary objects are mutable. Not like different objects, the dictionary merely shops a key together with its worth. Subsequently, the mixture of a key and its subsequent worth represents a single factor within the Python dictionary.  

Restrictions on Key Dictionaries

Beneath are enlisted some restrictions on the important thing dictionaries –

• A given key seems solely as soon as in a dictionary. Duplicates of keys will not be allowed. 
• It received’t make sense for those who map a specific key greater than as soon as. That is so as a result of the dictionary will map every key to its worth.
• In case of a duplication of a key, the final one will likely be thought of.
• If a key’s specified a second time after the creation of a dictionary, then the second time will likely be thought of as it should override the primary time.
• The important thing have to be immutable, which means the info sort might be an integer, string, tuple, boolean, and so forth. Subsequently, lists or one other dictionary can’t be used as they’re changeable.  

Easy methods to append a component to a key in a dictionary with Python?

Making a Dictionary

In Python, you possibly can create a dictionary simply utilizing mounted keys and values. The sequence of components is positioned inside curly brackets, and key: values are separated by commas. It have to be famous that the worth of keys might be repeated however can’t have duplicates. Additionally, keys ought to have immutable information varieties similar to strings, tuples, or numbers. 

Right here’s an instance –

# Making a Dictionary
# with Integer Keys
Dict = {1: 'Studying', 2: 'For', 3: Life}
print("nDictionary with using Integer Keys: ")
print(Dict)
  
# Making a Dictionary
# with Combined keys
Dict = {'Title': ‘Nice Studying’, 1: [1, 2, 3, 4]}
print("nDictionary with using Combined Keys: ")
print(Dict)

The output is :

Dictionary with using Integer Keys: 

{1: ‘Studying’, 2: ‘For’, 3: ‘Life’}

Dictionary with using Combined Keys: 

{‘Title’: ‘GreatLearning’, 1: [1, 2, 3, 4]}

Dictionary with integer keys

Right here’s methods to create a dictionary utilizing the integer keys –

# creating the dictionary
dict_a = {1 : "India", 2 : "UK", 3 : "US", 4 : "Canada"}

# printing the dictionary
print("Dictionary 'dict_a' is...")
print(dict_a)

# printing the keys solely
print("Dictionary 'dict_a' keys...")
for x in dict_a:
    print(x)

# printing the values solely
print("Dictionary 'dict_a' values...")
for x in dict_a.values():
    print(x)

# printing the keys & values
print("Dictionary 'dict_a' keys & values...")
for x, y in dict_a.gadgets():
    print(x, ':', y)

The output is:

Dictionary ‘dict_a’ is…

{1: ‘India’, 2: ‘USA’, 3: ‘UK’, 4: ‘Canada’}

Dictionary ‘dict_a’ keys…

1

2

3

4

Dictionary ‘dict_a’ values…

India

USA

UK

Canada

Dictionary ‘dict_a’ keys & values…

1 : India

2 : UK

3 : US

4 : Canada

Accessing components of a dictionary

Key names are used to entry components of a dictionary. To entry the weather, it is advisable to use sq. brackets ([‘key’]) with the important thing inside it. 

Right here’s an instance –

# Python program to show
# accessing a component from a dictionary
  
# Making a Dictionary
Dict = {1: 'Studying', 'identify': 'For', 3: 'Life'}
  
# accessing a component utilizing key
print("Accessing a component utilizing key:")
print(Dict['name'])
  
# accessing a component utilizing key
print("Accessing a component utilizing key:")
print(Dict[1])

The output is:

Accessing a component utilizing key:

For

Accessing a component utilizing key:

Life

Various technique 

There’s one other technique known as get() that’s used to entry components from a dictionary. On this technique, the secret is accepted as an argument and returned with a worth. 

Right here’s an instance –

# Making a Dictionary
Dict = {1: 'Studying', 'identify': 'For', 3: 'Life'}
  
# accessing a component utilizing get()
# technique
print("Accessing a component utilizing get:")
print(Dict.get(3))

The output is:

Accessing a component utilizing get:

Life

Deleting factor(s) in a dictionary

You’ll be able to delete components in a dictionary utilizing the ‘del’ key phrase.

The syntax is –

del dict['yourkey']  #This may take away the factor together with your key.

Use the next syntax to delete your entire dictionary –

del my_dict  # this may delete the dictionary with identify my_dict

One other various is to make use of the clear() technique. This technique helps to scrub the content material contained in the dictionary and empty it. The syntax is –

Allow us to verify an instance of the deletion of components that end in emptying your entire dictionary –

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}
del my_dict['username']  # it should take away "username": "ABC" from my_dict
print(my_dict)
my_dict.clear()  # until will make the dictionarymy_dictempty
print(my_dict)
delmy_dict # this may delete the dictionarymy_dict
print(my_dict)

The output is:

{’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’}

{}

Traceback (most up-to-date name final):

  File “foremost.py”, line 7, in <module>

    print(my_dict)

NameError: identify ‘my_dict’ shouldn’t be outlined

Deleting Aspect(s) from dictionary utilizing pop() technique

The dict.pop() technique can also be used to delete components from a dictionary. Utilizing the built-in pop() technique, you possibly can simply delete a component primarily based on its given key. The syntax is:

dict.pop(key, defaultvalue)

The pop() technique returns the worth of the eliminated key. In case of the absence of the given key, it should return the default worth. If neither the default worth nor the secret is current, it should give an error. 

Right here’s an instance that reveals the deletion of components utilizing dict.pop() –

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}
my_dict.pop("username")
print(my_dict)

The output is:

{’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’}

Appending factor(s) to a dictionary

It’s simple to append components to the present dictionary utilizing the dictionary identify adopted by sq. brackets with a key inside it and assigning a worth to it. 

Right here’s an instance:

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}

my_dict['name']='Nick'

print(my_dict)

The output is:

{‘username’: ‘ABC’, ’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’, ‘identify’: ‘Nick’}

Updating current factor(s) in a dictionary

For updating the present components in a dictionary, you want a reference to the important thing whose worth must be up to date. 

On this instance, we’ll replace the username from ABC to XYZ. Right here’s methods to do it:

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}

my_dict["username"] = "XYZ"

print(my_dict)

The output is:

{‘username’: ‘XYZ’, ’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’}

Insert a dictionary into one other dictionary

Allow us to contemplate an instance with two dictionaries – Dictionary 1 and Dictionary 2 as proven beneath –

Dictionary 1:

my_dict = {“username”: “ABC”, “e mail”: “abc@gmail.com”, “location”:”Gurgaon”}

Dictionary 2:

my_dict1 = {“firstName” : “Nick”, “lastName”: “Jonas”}

Now we wish to merge Dictionary 1 into Dictionary 2. This may be accomplished by making a key known as “identify” in my_dict and assigning my_dict1 dictionary to it. Right here’s methods to do it:

my_dict = {"username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"}

my_dict1 = {"firstName" : "Nick", "lastName": "Jonas"}

my_dict["name"] = my_dict1

print(my_dict)

The output is:

{‘username’: ‘ABC’, ’e mail’: ‘abc@gmail.com’, ‘location’: ‘Gurgaon’, ‘identify’: {‘firstName’: ‘Nick’, ‘lastName’: Jonas}}

As noticed within the output, the important thing ‘identify’ has the dictionary my_dict1. 

Fast Packages on Python Dictionary Append

1. Restrictions on Key Dictionaries:

Python dictionaries have some restrictions on their keys. Listed here are some examples of invalid dictionary keys:

bashCopy codemy_dict = {[1,2]: 'worth'}  # Lists are unhashable and can't be used as keys
my_dict = {{1:2}: 'worth'}  # Dictionaries are unhashable and can't be used as keys
my_dict = {'a': 'value1', 'a': 'value2'}  # Duplicate keys will not be allowed in dictionaries

2. Easy methods to append a component to a key in a dictionary with Python:

You’ll be able to append a component to an inventory that may be a worth related to a key in a dictionary like this:

cssCopy codemy_dict = {'key': [1, 2, 3]}
my_dict['key'].append(4)
print(my_dict)  # Output: {'key': [1, 2, 3, 4]}

3. Accessing components of a dictionary:

You’ll be able to entry components in a dictionary utilizing their keys like this:

bashCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
print(my_dict['key1'])  # Output: 'value1'

You too can use the get() technique to entry dictionary components. This technique returns None if the secret is not current within the dictionary:

bashCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
print(my_dict.get('key1'))  # Output: 'value1'
print(my_dict.get('key3'))  # Output: None

4. Deleting factor(s) in a dictionary:

You’ll be able to delete a component from a dictionary utilizing the del key phrase like this:

cssCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
del my_dict['key1']
print(my_dict)  # Output: {'key2': 'value2'}

5. Deleting Aspect(s) from dictionary utilizing pop() technique:

You too can delete a component from a dictionary utilizing the pop() technique. This technique removes the key-value pair from the dictionary and returns the worth:

goCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
worth = my_dict.pop('key1')
print(my_dict)  # Output: {'key2': 'value2'}
print(worth)  # Output: 'value1'

6. Appending factor(s) to a dictionary:

You’ll be able to append a brand new key-value pair to a dictionary like this:

cssCopy codemy_dict = {'key1': 'value1'}
my_dict['key2'] = 'value2'
print(my_dict)  # Output: {'key1': 'value1', 'key2': 'value2'}

7. Updating current factor(s) in a dictionary:

You’ll be able to replace an current factor in a dictionary by assigning a brand new worth to its key like this:

cssCopy codemy_dict = {'key1': 'value1', 'key2': 'value2'}
my_dict['key2'] = 'new_value'
print(my_dict)  # Output: {'key1': 'value1', 'key2': 'new_value'}

8. Insert a dictionary into one other dictionary:

You’ll be able to insert a dictionary into one other dictionary through the use of the replace() technique like this:

bashCopy codemy_dict1 = {'key1': 'value1'}
my_dict2 = {'key2': 'value2'}
my_dict1.replace(my_dict2)
print(my_dict1)  # Output:

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