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Python: Select a random element from a list, set, dictionary and a file from a directory

Python module: Exercise-2 with Solution

Write a Python program to select a random element from a list, set, dictionary (value) and a file from a directory.

Use random.choice

Sample Solution:

Python Code:

import random
import os
print("Select a random element from a list:")
elements = [1, 2, 3, 4, 5]
print(random.choice(elements))
print(random.choice(elements))
print(random.choice(elements))
print("\nSelect a random element from a set:")
elements = set([1, 2, 3, 4, 5])
# convert to tuple because sets are invalid inputs
print(random.choice(tuple(elements)))
print(random.choice(tuple(elements)))
print(random.choice(tuple(elements)))
print("\nSelect a random value from a dictionary:")
d = {"a": 1, "b": 2, "c": 3, "d": 4, "e": 5}
key = random.choice(list(d))
print(d[key])
key = random.choice(list(d))
print(d[key])
key = random.choice(list(d))
print(d[key]) 
print("\nSelect a random file from a directory.:")
print(random.choice(os.listdir("/")))

Sample Output:

Select a random element from a list:
3
4
5

Select a random element from a set:
1
3
5

Select a random value from a dictionary:
5
4
4

Select a random file from a directory.:
proc

Flowchart:

Flowchart: Select a random element from a list, set, dictionary and a file from a directory.

Visualize Python code execution:

The following tool visualize what the computer is doing step-by-step as it executes the said program:


Python Code Editor:

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Next: Write a Python program to generate a random alphabetical character, alphabetical string and alphabetical string of a fixed length.

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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