Python: Retrieve the value of the nested key indicated by the given selector list from a dictionary or list
Python List: Exercise - 225 with Solution
Write a Python program to retrieve the value of the nested key indicated by the given selector list from a dictionary or list.
- Use functools.reduce() to iterate over the selectors list.
- Apply operator.getitem() for each key in selectors, retrieving the value to be used as the iteratee for the next iteration.
Sample Solution:
Python Code:
from functools import reduce
from operator import getitem
def get(d, selectors):
return reduce(getitem, selectors, d)
users = {
'freddy': {
'name': {
'first': 'Fateh',
'last': 'Harwood'
},
'postIds': [1, 2, 3]
}
}
print(get(users, ['freddy', 'name', 'last']))
print(get(users, ['freddy', 'postIds', 1]))
Sample Output:
Harwood 2
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Previous: Write a Python program to create a list with the unique values filtered out.
Next: Write a Python program to get a list of elements that exist in both lists, after applying the provided function to each list element of both.
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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
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