Python: Sort one list based on another list containing the desired indexes
Python List: Exercise - 218 with Solution
Write a Python program to sort one list based on another list containing the desired indexes.
- Use zip() and sorted() to combine and sort the two lists, based on the values of indexes.
- Use a list comprehension to get the first element of each pair from the result
- Use the reverse parameter in sorted() to sort the dictionary in reverse order, based on the third argument
Sample Solution:
Python Code:
def sort_by_indexes(lst, indexes, reverse=False):
return [val for (_, val) in sorted(zip(indexes, lst), key=lambda x: \
x[0], reverse=reverse)]
l1 = ['eggs', 'bread', 'oranges', 'jam', 'apples', 'milk']
l2 = [3, 2, 6, 4, 1, 5]
print(sort_by_indexes(l1, l2))
print(sort_by_indexes(l1, l2, True))
Sample Output:
['apples', 'bread', 'eggs', 'jam', 'milk', 'oranges'] ['oranges', 'milk', 'jam', 'eggs', 'bread', 'apples']
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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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