What is dictionary with types in Python?

Welcome to the world of Python dictionaries! In this article, we will explore the fascinating dictionary data type in Python, which sets it apart from other programming languages.

A dictionary allows you to organize data based on specific "keys" and their corresponding "values." By accessing a value using its key, you can retrieve and manipulate data efficiently.

To demonstrate the power of dictionaries, we will use a sample dictionary called "clothDict" throughout the examples. You can write according to your program.

Dictionary in Python

A dictionary data type like set in Python is a special data structure not seen in other programming languages. Here the data is organized according to a specific "key" and "value". "Value" is accessed with "key".

The dictionary is written in the second parenthesis.

See an example;

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"} #Defining a dict

print(clothDict)

Result-

{'name': 'Shirt', 'size': 'Long', 'type': 'Casual'}

Also read: String in Python

Accessing a specific element

A "key" is required to access the value of a particular element in the dictionary.

Example;

clothDict=

{"name":"Shirt",

"size":"Long",

"type":"Casual" }#Defining a dict

outputDict=clothDict["name"]

print(outputDict)

Result-

Shirt

Similarly, to change any of the values, "key" is to be done through it.

Example of a dictionary in python.

clothDict=

{"name":"Shirt",

"size":"Long",

"type":"Casual" }#Defining a dict

clothDict["size"]="small"

print(clothDict)

Result-

{'type': 'Casual', 'size': 'small', 'name': 'Shirt'}

Loop over dictionary

Keys are basically found by looping through the dictionary.

Lets see an example of loop in a dictionary in python.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" }#Defining a dict

for i in clothDict:

print(i)

Result-

name

type

size

Since the key is obtained through the loop, the value can also be extracted in the same way as before.

Example of a loop in a dictionary in python.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" }#Defining a dict

for i in clothDict:

print(clothDict[i])

Result-

Shirt

Casual

Long

Also read: Conditional statement, Lopp in Python

Dictionary methods

Dictionary has several built-in methods, see them (in alphabetical order) –

clear()

This method deletes all existing elements in the dictionary.

See clear() method in python

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" }#Defining a dict

clothDict.clear() # Clear() classmethod

print(clothDict)

Result-

{}

copy()

This method is used to copy one dictionary to another dictionary.

Example of dictionary copy() method in python

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" }#Defining a dict

outputDict=clothDict.copy() # copy() classmethod

print(outputDict)

Result-

{'name': 'Shirt', 'type': 'Casual', 'size': 'Long'}

del()

This method is used to delete a specific element of the dictionary.

Lets see an example of dictionary del() method in python.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" }#Defining a dict

del clothDict["size"] # del() method

print(clothDict)

Result-

{'name': 'Shirt', 'type': 'Casual'}

The del() method can also be used to delete the entire dictionary.

See example of dictionary 'del()' method in python;

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" } # Defining a dict

del clothDict # del() method

print(clothDict)

Result-

Traceback (most recent call last):

File "main.py", line 10, in <module> print(clothDict)

NameError: name 'clothDict' is not defined

get()

This method is used to access a specific element of a dictionary.

Example of dictionary 'get()' method in python;

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"}#Defining a dict

outputValue=clothDict.get("name") # get() classmethod

print(outputValue)

Result-

Shirt

keys()

This method displays all the keys in the dictionary.

An example of dictionary keys() method in python

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"}# Defining a dict

outputValue=clothDict.keys() # keys() classmethod

print(outputValue)

Result-

dict_keys(['type', 'size', 'name'])

len()

The len() method is used to find the number of entries in a dictionary.

Dictionary len() method in python;

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"} #Defining a dict

dictLength=len(clothDict)# len() method

print(dictLength)

Result-

pop()

The pop() method is used to remove a specific element from the dictionary.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"} #Defining a dict

outputValue=clothDict.pop("type") # pop() method

print(outputValue) # popped value

print(clothDict)

Result-

Casual {'name': 'Shirt', 'size': 'Long'}

popitem()

The popitem() method deletes an element from a random selection method.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"} # Defining a dict

outputValue=clothDict.popitem() # popitem() method

print(outputValue) # popped value

print(clothDict)

Result-

('size', 'Long') {'type': 'Casual', 'name': 'Shirt'}

setdefault()

The setdefault() method sets a default value. If a dictionary contains that particular key, then the value of that dictionary will be considered, otherwise the default value will be considered.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual"} #Defining a dict

outputValue=clothDict.setdefault("size","short") # setdefault() method

print(outputValue)

print(clothDict)

outputValue2=clothDict.setdefault("color","white") # setdefault() method

print(outputValue2)

print(clothDict)

Result-

Long

{'size': 'Long', 'type': 'Casual', 'name': 'Shirt'}

white

{'size': 'Long', 'color': 'white', 'type': 'Casual ', 'name': 'Shirt'}

update()

The update() method is used to add a value to the dictionary.

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" } #Defining a dict

clothDict.update({"color":"white"})

# update() method

print(clothDict)

Result-

{'type': 'Casual', 'name': 'Shirt', 'color': 'white', 'size': 'Long'}

values()

This method is somewhat similar to the keys() method. The values() method separates all the values in a dictionary.

See an example of dictionary values() method in python;

clothDict=

{"name":"Shirt",

"size": "Long",

"type":"Casual" } #Defining a dict

outputDict=clothDict.values() # values() method

print(outputDict)

Result-

dict_values(['Long', 'Shirt', 'Casual'])

Also read: Python variables and operators

Recursion in Python

Recursion is an important topic in programming. Recursion is when a function calls itself. Python allows the use of recursion. When talking about recursion, factorial comes to mind first, now let's look at recursion with the help of this factorial example -

This program is an example of recursion in python;

def recursion_python(value):

if(value==1):

return 1

else:

return (value*recursion_python(value-1))

print(recursion_python(5)) # function call

Result-

120

Notice here in line 4 "return(value*recursion_python(value-1))" the function name recusrion_python() is called again inside it.

When coming to the 4th line, value i.e. 5 is multiplied with value-1 i.e. 4; Similarly when this function is called again it is multiplied by value-1 i.e. 3.

In this way, when the value becomes 1, it exits from here. So the order of multiplication is 5,4,3,2,1

Hope you understand recursion well.

Conclusion:

Python dictionaries offer a powerful and unique way to organize and manipulate data. The dictionary data type, unlike other programming languages, allows you to store data based on specific keys and their corresponding values. By accessing values using their keys, you can efficiently retrieve and modify data within a dictionary.

Throughout this article, we explored various aspects of Python dictionaries using a sample dictionary called "clothDict." We learned how to define dictionaries, access specific elements using keys, and modify values by updating the corresponding keys. Additionally, we explored looping over dictionaries to access both keys and values dynamically.

We briefly discussed the Python programming concept of recursion. Recursion is a powerful technique where a function calls itself, allowing for elegant and concise solutions to certain problems. We illustrated recursion with an example of calculating the factorial of a number.

By understanding and utilizing Python dictionaries effectively, you can enhance your programming capabilities and efficiently manage complex data structures. Python's dictionary data type proves to be a valuable tool for developers, making it a fundamental aspect of the language.

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