Python 3


"The first Python course that simply amazed me. Very well explained and easy to understand." (Alexandru Cosmin)

"The best Python course in Romania." (Iulian Geană)

PAGE 1 / 5
Dictionaries in Python
Home >>> Online Lessons, Python 3

What is a Dictionary?

In Python, a dictionary (data type dict) is an unordered, indexed, and mutable collection of data that contains any number of key-value pairs (obviously, the key is unique):

Below is an initial example of a dictionary:
Editor -
Console/Output done

For each key word on the left, we have associated a value (an antonym) on the right. We use the colon character ":" to make the association, and to separate pairs, the comma character ",". All are written within curly braces, similar to a data set.

The length of the dictionary is not 6, but of course 3, which is the number of key (pairs) we have entered.

A dictionary is not ordered with actual indexes, but access is done using the key words from the pairs. Thus, we write antonyms['tall'] to get the value 'short'.

If we try to write antonyms[1], we will get an interpretation error:

Moreover, if a key word is not found in the data structure, an exception/error will be displayed:

So, the index (key) was not found.
Proceed to the next page.
 home   list  CONTENTS   perm_identity   arrow_upward