Question

In Python, I’ve got a list of dictionaries that looks like this:

matchings = [     {'id': 'someid1', 'domain': 'somedomain1.com'},     {'id': 'someid2', 'domain': 'somedomain2.com'},     {'id': 'someid3', 'domain': 'somedomain3.com'} ] 

and, I have a variable:

the_id = 'someid3' 

What’s the most efficient way to retrieve the domain value of the item?

Answer 1

You can use a list comprehension:

domains = [matching['domain'] for matching in matchings if matching['id'] == the_id] 

Which follows the format standard format of:

resulting_list = [item_to_return for item in items if condition] 

And basically encapsulates all the following functionality:

domains = [] for matching in matchings:     if matching['id'] == the_id:         domains.append(matching['domain']) 

All that functionality is represented in a single line using list comprehensions.