How to use map() with dictionary comprehension in Python-CodePudding

I am trying to use map() on a list of dictionaries to get a name and id only.

My input:

employees = [
   {"id": 12113, "name": "Jim", "department": "Sales"},
   {"id": 12342, "name": "Michael", "department": "Management"},
   {"id": 23312, "name": "Dwight", "department": "Sales"},
]

What I want my function to return is a dictionary where each key is the employee's name and the value is the employee's ID.

My function currently contains what is below but isn't returning values, only: <map object at 0x7f3b0bb6d460>, <map object at 0x7f78e7242670>.

My code:

def name_id(employees):

   name_and_ids = [{map(('name', 'id'), emp) for emp in employees}]
   print(list(name_id)) ### to see if what I want is being output or not
   return name_and_ids

I am calling my function with:

  print(f"Name and ids: {name_id(employees)}")

I am fairly new to python and am getting confused with comprehensions in general, whether list or dictionary comprehensions. I did see you can use dict and/or zip but would like to learn something new with map().

Any advice/help to push me in the right direction of getting what I want would be much appreciated.

CodePudding user response：

What I want my function to return is a dictionary where each key is the employee's name and the value is the employee's ID.

You need a dictionary comprehension:

result = {
    emp['name']: emp['id']
    for emp in employees
}

map is not an appropriate tool for the job, because it converts N things to N other things, whereas you need to convert N things (3 employees) into one thing (a dict). If you insist, you could use map to convert the source list into a list of key-value tuples and then apply dict to the result:

from operator import itemgetter

result = dict(
    map(itemgetter('name', 'id'), employees)
)

This style is not considered "pythonic" though.

CodePudding user response：

The map function doesn't do anything related to what you want here. It's leading you astray.

Instead, just do the mapping you want yourself in the dict comprehension you already have:

name_and_ids = {emp['name']: emp['id'] for emp in employees}