---
title: "Dictionary in Python"
url: https://blog.creatuwebpymes.com/en/dictionary-in-python/
date: 2025-03-10
modified: 2025-03-16
author: "franciscobritoda69"
image: https://blog.creatuwebpymes.com/wp-content/uploads/2025/03/Python-Dictionaries.webp
categories: ["Python code"]
tags: ["python code", "python code tutorials"]
type: post
lang: en
---

# Dictionary in Python

## **Dictionaries in Python Language**

A dictionary in Python is a collection of pairwise information in the format key:values. The correct syntax is { key : value }

The Python dictionary also stores multiple pieces of information like Lists in Python do, but with the difference that dictionaries do not use numbers in their indexes, instead the indexes are keys.

At the same time, dictionary keys are set manually, unlike the indexes in Lists which are assigned automatically by Python.

Keys in a dictionary can NOT be duplicated, i.e. they must be UNIQUE.

```
car = {'make':'Renault','colour':'red','engine':1.6}
```

The keys in the example above would be - make, colour, engine - so there could not be - make or colour - more than once. That is why they are said to be unique.

## **Creating a dictionary in Python**

There are several ways to create a dictionary in Python. On the one hand we have the **dict ( )** constructor option and on the other hand, the use of the  **{ }**.

```
# create a dictionary with the dict ( ) constructorfruit = dict( )# We want to see on the console the type of data fruit isprint(type(fruit)) # dictionary type
```

As we see above we have created a dictionary called - fruit - and we have assigned the constructor - dict ( ) to it. This way it will create an empty dictionary with no elements.

When using **print(type(fruit))** we want to display the type of - fruit - on the screen and we get **< class 'dict'>** as a result indicating that it is a dictionary.

```
# create the dictionary with {} fruit = { }# Show on the console the type of data fruit isprint(type(fruit)) # dictionary type
```

In this second method we use the **{ }** instead of dict( ). And everything else is exactly the same as in the previous case.

We create an empty dictionary with no elements called - fruit.

By using print(type(fruit)) we want the type of - fruit - to be displayed on the screen and we get **< class 'dict'>** confirming that it is a dictionary.

### **Accessing a dictionary in Python**

To understand how we access the elements of a dictionary in Python, the syntax is **dict.**
****

```
# Let´s say we have a new dictionary called numbersnumbers = { 'uno':'one', 'dos':'two', 'tres':'three' }# if we want to access to value threenumbers['tres']# On the console will showthree
```

In the above example for the key - one - we have the value - one, etc. So for key tres we have the value **three**.

If by mistake we pass a key that is not part of the dictionary, Python will return an error message - **KeyError 'wrong key entered**'.

### **Adding items to a dictionary in Python**

Tenemos varias formas de añadir elementos a un diccionario en Python. La primera opción es con la sintaxis siguiente: **diccionario = value**.

```
# numbers dictionary has new data as new examplenumbers = { 10:'diez', 20:'veinte', 30:'treinta', 40:'cuarenta' }# if we want to add another elementnumberos[50] = 'cincuenta'# On console we will seenumbers = { 10:'diez', 20:'veinte', 30:'treinta', 40:'cuarenta', 50:'cincuenta }
```

The other method for adding items to a dictionary is with the **update ( )** method.

The syntax of the update method is **dictionary.update({key:value})** . It is important to mention that the argument we pass inside the parenthesis of update must be between** { }**.

```
# dictionary called carcar = { 'make':'Fiat','colour':'Green','doors':'three' }# We add a new element to car with update()car.update({'engine':'petrol'}# After the updatecar = { 'make':'Fiat','colour':'Green','doors':'three','engine':'petrol' }
```

If you need to add more than one element with the update ( ) method, you can do so by assigning them a variable and then inserting the variable inside the update brackets.

```
# car dictionarycar = { 'make':'Fiat','colour':'Green','doors':'three' }# Add a new element to car with update()# Assign the new key:values to a variable called new_carnew_car = {'engine':'petrol','year':2010}# Update info car.update(new_car)# car will be updated like thiscar = { 'engine':'Fiat','colour':'Green','doors':'three','engine':'petrol','year':2010 }
```

 

### **Deleting items from a dictionary in Python**

We will see two options for deleting elements in a dictionary: **pop ( ) **and **del ( )**

With the pop( ) method we remove the element from the dictionary and return the element we have removed on the screen. When using pop() we must pass as argument the key of the element we want to remove.

```
# Using the car dictionary example we will remove the value of key -> colourcar = { 'engine':'Fiat','colour':'Green','doors':'three','engine':'petrol','year':2010 }element_removed = car.pop('colour')# on the console print(element_removed)Green
```

 

On the other hand, with the** del ( )** method, when we delete the element it is not returned on screen, as in the case of pop ( ).

With del ( ) we also use the key of the element we want to remove from the dictionary.

The syntax of del () is **del dictionary**

```
# Using the car dictionary example we will remove the value of key -> yearcar = { 'engine':'Fiat','doors':'three','engine':'petrol','year':2010 }# Remove the value of key -> yeardel car['year']# on the console print(car){ 'engine':'Fiat','doors':'three','engine':'petrol' }
```

 

### **Read items from a dictionary in Python**

There are several ways to read items from a dictionary.

**dict.items( )** -> this method returns both the keys and the values of the dictionary.

**dict.keys( )** -> returns only the dictionary keys.

**dict.values( )** -> returns only the values of the dictionary.

 

```
# We are going to work with a new dictionary called cadenacadena = {1:'one',2:'two',3:'three',4:'four',5:'five'}
```

```
# If we want to get the data from cadena with dict.items( )for key,value in cadena.items( ): print(key,':',value)# on console will show keys and values1:one2:two3:three4:four5:five
```

```
# If we want to get the data from cadena with dict.keys( )for i in cadena.keys( ): print(i)# on console will show just the keys12345
```

```
# If we want to get the data from cadena with dict.values( )for i in cadena.values( ): print(i)# on console will show just the valuesonetwothreefourfive
```

In short, the Python dictionary allows us a wide variety of options when it comes to handling data. This is a lesson for Python ´s students as they ask about it when they start programming in this language.

If you want to continue learning how to program in Python, you can find more resources in this link. (https://www.udemy.com/user/musa-arda/)

Creatuwebpymes, is a (https://creatuwebpymes.com/en/web-design-lanzarote/) in the Canary Islands that ❤️ programming.

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