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Python: Map dictionary

Python dictionary: Exercise-70 with Solution

Write a Python program to map the values of a given list to a dictionary using a function, where the key-value pairs consist of the original value as the key and the result of the function as the value.

  • Use map() to apply fn to each value of the list.
  • Use zip() to pair original values to the values produced by fn.
  • Use dict() to return an appropriate dictionary.

Sample Solution:

Python Code:

def test(itr, fn):
  return dict(zip(itr, map(fn, itr)))
print(test([1, 2, 3, 4], lambda x: x * x))

Sample Output: 

{1: 1, 2: 4, 3: 9, 4: 16}

Flowchart:

Flowchart: Map dictionary.

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Previous: Write a Python program to group the elements of a given list based on the given function.
Next: Write a Python program to retrieve the value of the nested key indicated by the given selector list from a dictionary or list.

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Python: Tips of the Day

Find current directory and file's directory:

To get the full path to the directory a Python file is contained in, write this in that file:

import os 
dir_path = os.path.dirname(os.path.realpath(__file__))

(Note that the incantation above won't work if you've already used os.chdir() to change your current working directory, since the value of the __file__ constant is relative to the current working directory and is not changed by an os.chdir() call.)

To get the current working directory use

import os
cwd = os.getcwd()

Documentation references for the modules, constants and functions used above:

  • The os and os.path modules.
  • The __file__ constant
  • os.path.realpath(path) (returns "the canonical path of the specified filename, eliminating any symbolic links encountered in the path")
  • os.path.dirname(path) (returns "the directory name of pathname path")
  • os.getcwd() (returns "a string representing the current working directory")
  • os.chdir(path) ("change the current working directory to path")

Ref: https://bit.ly/3fy0R6m