Learn how 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 enable 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 sturdy 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 should not have an append() methodology like lists do, a number of methods exist so as to add new key-value pairs to a dictionary. On this weblog publish, we’ll discover a few of these strategies and focus on when to make use of each. So, let’s dive in!

Dictionary in Python

A dictionary is a needed information sort in Python programming. It’s a assortment of information values which are unordered. Python dictionary is used to retailer objects during which 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 solely 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. Due to this fact, the mix 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 are usually not allowed. 
• It gained’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 can be thought-about.
• If a secret’s specified a second time after the creation of a dictionary, then the second time can be thought-about as it is going to override the primary time.
• The important thing should be immutable, that means the information sort may be an integer, string, tuple, boolean, and so on. Due to this fact, lists or one other dictionary can’t be used as they’re changeable.  

Learn how to append a component to a key in a dictionary with Python?

Making a Dictionary

In Python, you’ll be able to create a dictionary simply utilizing mounted keys and values. The sequence of parts is positioned inside curly brackets, and key: values are separated by commas. It should be famous that the worth of keys may be repeated however can’t have duplicates. Additionally, keys ought to have immutable information varieties corresponding 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 Blended keys
Dict = 'Identify': ‘Nice Studying’, 1: [1, 2, 3, 4]
print("nDictionary with using Blended Keys: ")
print(Dict)

The output is :

Dictionary with using Integer Keys: 

1: ‘Studying’, 2: ‘For’, 3: ‘Life’

Dictionary with using Blended Keys: 

‘Identify’: ‘GreatLearning’, 1: [1, 2, 3, 4]

Dictionary with integer keys

Right here’s tips on how 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.objects():
    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 parts of a dictionary

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

Right here’s an instance –

# Python program to display
# accessing a component from a dictionary
  
# Making a Dictionary
Dict = 1: 'Studying', 'title': '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 methodology 

There’s one other methodology known as get() that’s used to entry parts from a dictionary. On this methodology, the bottom line is accepted as an argument and returned with a price. 

Right here’s an instance –

# Making a Dictionary
Dict = 1: 'Studying', 'title': 'For', 3: 'Life'
  
# accessing a component utilizing get()
# methodology
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 possibly can delete parts in a dictionary utilizing the ‘del’ key phrase.

The syntax is –

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

Use the next syntax to delete the whole dictionary –

del my_dict  # this may delete the dictionary with title my_dict

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

Allow us to examine an instance of the deletion of parts that lead to emptying the whole dictionary –

my_dict = "username": "ABC", "e mail": "abc@gmail.com", "location":"Gurgaon"
del my_dict['username']  # it is going to 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 “major.py”, line 7, in <module>

    print(my_dict)

NameError: title ‘my_dict’ is just not outlined

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

The dict.pop() methodology can also be used to delete parts from a dictionary. Utilizing the built-in pop() methodology, you’ll be able to simply delete a component based mostly on its given key. The syntax is:

dict.pop(key, defaultvalue)

The pop() methodology returns the worth of the eliminated key. In case of the absence of the given key, it is going to return the default worth. If neither the default worth nor the bottom line is current, it is going to give an error. 

Right here’s an instance that reveals the deletion of parts 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 parts to the present dictionary utilizing the dictionary title adopted by sq. brackets with a key inside it and assigning a price 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’, ‘title’: ‘Nick’

Updating current factor(s) in a dictionary

For updating the present parts 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 tips on how 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 need to merge Dictionary 1 into Dictionary 2. This may be executed by making a key known as “title” in my_dict and assigning my_dict1 dictionary to it. Right here’s tips on how 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’, ‘title’: ‘firstName’: ‘Nick’, ‘lastName’: Jonas

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

Fast Applications 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 are usually not allowed in dictionaries

2. Learn how to append a component to a key in a dictionary with Python:

You possibly can append a component to an inventory that could 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 parts of a dictionary:

You possibly can entry parts in a dictionary utilizing their keys like this:

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

It’s also possible to use the get() methodology to entry dictionary parts. This methodology returns None if the bottom line 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 possibly can 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() methodology:

It’s also possible to delete a component from a dictionary utilizing the pop() methodology. This methodology 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 possibly can 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 possibly can 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 possibly can insert a dictionary into one other dictionary through the use of the replace() methodology like this:

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

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