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Python: Check if a set is a subset of another set

Python sets: Exercise-10 with Solution

Write a Python program to check if a set is a subset of another set.

From Wikipedia,
In mathematics, a set A is a subset of a set B if all elements of A are also elements of B; B is then a superset of A. It is possible for A and B to be equal; if they are unequal, then A is a proper subset of B. The relationship of one set being a subset of another is called inclusion (or sometimes containment). A is a subset of B may also be expressed as B includes (or contains) A or A is included (or contained) in B.

Python Sets: Check if a set is a subset of another set.

Sample Solution:

Python Code:

print("Check if a set is a subset of another set, using comparison operators and issubset():\n")
setx = set(["apple", "mango"])
sety = set(["mango", "orange"])
setz = set(["mango"])
print("x: ",setx)
print("y: ",sety)
print("z: ",setz,"\n")
print("If x is subset of y")
print(setx <= sety)
print(setx.issubset(sety))
print("If y is subset of x")
print(sety <= setx)
print(sety.issubset(setx))
print("\nIf y is subset of z")
print(sety <= setz)
print(sety.issubset(setz))
print("If z is subset of y")
print(setz <= sety)
print(setz.issubset(sety))

Sample Output: 

Check if a set is a subset of another set, using comparison operators and issubset():

x:  {'mango', 'apple'}
y:  {'mango', 'orange'}
z:  {'mango'} 

If x is subset of y
False
False
If y is subset of x
False
False

If y is subset of z
False
False
If z is subset of y
True
True

Pictorial Presentation:

Python Sets: Check if a set is a subset of another set.
Python Sets: Check if a set is a subset of another set.

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Previous: Write a Python program to create a symmetric difference.
Next: Write a Python program to create a shallow copy of sets.

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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