{"id":582,"date":"2020-10-16T04:48:34","date_gmt":"2020-10-16T04:48:34","guid":{"rendered":"https:\/\/www.pythontutorial.net\/?page_id=582"},"modified":"2025-03-27T03:02:13","modified_gmt":"2025-03-27T03:02:13","slug":"python-dictionary-comprehension","status":"publish","type":"page","link":"https:\/\/www.pythontutorial.net\/python-basics\/python-dictionary-comprehension\/","title":{"rendered":"Python Dictionary Comprehension"},"content":{"rendered":"\n

Summary<\/strong>: in this tutorial, you’ll learn about Python dictionary comprehension to transform or filter items in a dictionary.<\/p>\n\n\n\n

Introduction to Python dictionary comprehension #<\/a><\/h2>\n\n\n\n

A dictionary comprehension allows you to run a for<\/code> loop<\/a> on a dictionary<\/a> and do something on each item like transforming or filtering and returns a new dictionary.<\/p>\n\n\n\n

Unlike a for<\/code> loop, a dictionary comprehension offers a more expressive and concise syntax when you use it correctly.<\/p>\n\n\n\n

Here is the general syntax for dictionary comprehension:<\/p>\n\n\n

{key<\/span>:value for (key,value) in dict.items<\/span>() if condition}<\/code><\/span>Code language:<\/span> CSS<\/span> (<\/span>css<\/span>)<\/span><\/small><\/pre>\n\n\n
This dictionary comprehension expression returns a new dictionary whose item specified by the expression key: value<\/code><\/p>\n\n\n\n
Python dictionary comprehension examples #<\/a><\/h2>\n\n\n\n
We’ll take a look at how to use dictionary comprehension to transform and filter items in a dictionary.<\/p>\n\n\n\n
Using Python dictionary comprehension to transform a dictionary #<\/a><\/h3>\n\n\n\n
Suppose that you have the following dictionary whose items are stock symbol and price:<\/p>\n\n\n
stocks = {\n    'AAPL'<\/span>: 121<\/span>,\n    'AMZN'<\/span>: 3380<\/span>,\n    'MSFT'<\/span>: 219<\/span>,\n    'BIIB'<\/span>: 280<\/span>,\n    'QDEL'<\/span>: 266<\/span>,\n    'LVGO'<\/span>: 144<\/span>\n}<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
To increase the price of each stock by 2%, you may come up with a for loop like this:<\/p>\n\n\n
stocks = {\n    'AAPL'<\/span>: 121<\/span>,\n    'AMZN'<\/span>: 3380<\/span>,\n    'MSFT'<\/span>: 219<\/span>,\n    'BIIB'<\/span>: 280<\/span>,\n    'QDEL'<\/span>: 266<\/span>,\n    'LVGO'<\/span>: 144<\/span>\n}\n\nnew_stocks = {}\nfor<\/span> symbol, price in<\/span> stocks.items():\n    new_stocks[symbol] = price*1.02<\/span>\n\nprint(new_stocks)\n<\/code><\/span>Code language:<\/span> Python<\/span> (<\/span>python<\/span>)<\/span><\/small><\/pre>\n\n\n
Output:<\/p>\n\n\n
{'AAPL': 123.42, 'AMZN': 3447.6, 'MSFT': 223.38, 'BIIB': 285.6, 'QDEL': 271.32, 'LVGO': 146.88}<\/code><\/span>Code language:<\/span> Shell Session<\/span> (<\/span>shell<\/span>)<\/span><\/small><\/pre>\n\n\n
How it works.<\/p>\n\n\n\n
Try it<\/a><\/p>\n\n\n\n