Python dictionary is a set kind 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 way known as hashing to map keys to their related values. They’re a sturdy information construction that lets you retailer and manipulate information in a key-value pair format. One widespread activity when working with dictionaries is to append new values to an present dictionary. Whereas Python dictionaries wouldn’t 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 talk about when to make use of each. So, let’s dive in!
Dictionary in Python
A dictionary is a crucial information kind in Python programming. It’s a assortment of information values which are unordered. Python dictionary is used to retailer gadgets through 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 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
Under are enlisted some restrictions on the important thing dictionaries –
A given key seems solely as soon as in a dictionary. Duplicates of keys usually are not allowed.
It gained’t make sense if you happen to map a selected 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 is specified a second time after the creation of a dictionary, then the second time can be thought-about as it should override the primary time.
The important thing should be immutable, that means the information kind could be an integer, string, tuple, boolean, and many others. 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 parts is positioned inside curly brackets, and key: values are separated by commas. It should be famous that the worth of keys could be repeated however can’t have duplicates. Additionally, keys ought to have immutable information sorts akin 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 = {‘Title’: ‘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:
{‘Title’: ‘GreatLearning’, 1: [1, 2, 3, 4]}
Dictionary with integer keys
Right here’s how you can 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 parts of a dictionary
Key names are used to entry parts of a dictionary. To entry the weather, you want to use sq. brackets ([‘key’]) with the important thing inside it.
Right here’s an instance –
# Python program to exhibit
# 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
Different methodology
There’s one other methodology known as get() that’s used to entry parts from a dictionary. On this methodology, the secret’s 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()
# 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 –
Use the next syntax to delete the complete dictionary –
One other various is to make use of the clear() methodology. This methodology helps to wash 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 end in emptying the complete 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 can 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’ isn’t outlined
Deleting Aspect(s) from dictionary utilizing pop() methodology
The dict.pop() methodology can be used to delete parts from a dictionary. Utilizing the built-in pop() methodology, you possibly can simply delete a component based mostly on its given key. The syntax is:
The pop() methodology 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’s current, it should 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 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 present 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 how you can 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 under –
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 achieved by making a key known as “identify” in my_dict and assigning my_dict1 dictionary to it. Right here’s how you can 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 Applications on Python Dictionary Append
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 usually are not allowed in dictionaries
Easy methods 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]}
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’
You can even use the get() methodology to entry dictionary parts. This methodology returns None if the secret’s 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
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’}
Deleting Aspect(s) from dictionary utilizing pop() methodology:
You can even 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’
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’}
Updating present factor(s) in a dictionary:
You possibly can replace an present 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’}
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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