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Python: Create set difference

Python sets: Exercise-8 with Solution

Write a Python program to create set difference.

Sample Solution-1:

Using difference() Method

Python Code:

setc1 = set(["green", "blue"])
setc2 = set(["blue", "yellow"])
print("Original sets:")
print(setc1)
print(setc2)
r1 = setc1.difference(setc2)
print("\nDifference of setc1 - setc2:")
print(r1)
r2 = setc2.difference(setc1)
print("\nDifference of setc2 - setc1:")
print(r2)
setn1 = set([1, 1, 2, 3, 4, 5])
setn2 = set([1, 5, 6, 7, 8, 9])
print("\nOriginal sets:")
print(setn1)
print(setn2)
r1 = setn1.difference(setn2)
print("\nDifference of setn1 - setn2:")
print(r1)
r2 = setn2.difference(setn1)
print("\nDifference of setn2 - setn1:")
print(r2)

Sample Output:

Original sets:
{'green', 'blue'}
{'yellow', 'blue'}

Difference of setc1 - setc2:
{'green'}

Difference of setc2 - setc1:
{'yellow'}

Original sets:
{1, 2, 3, 4, 5}
{1, 5, 6, 7, 8, 9}

Difference of setn1 - setn2:
{2, 3, 4}

Difference of setn2 - setn1:
{8, 9, 6, 7} 

Pictorial Presentation:

NumPy Sets: Create set difference.

Visualize Python code execution:

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


Sample Solution-2:

Using - Operator

Python Code:

setc1 = set(["green", "blue"])
setc2 = set(["blue", "yellow"])
print("Original sets:")
print(setc1)
print(setc2)
r1 = setc1 - setc2
print("\nDifference of setc1 - setc2:")
print(r1)
r2 = setc2 - setc1
print("\nDifference of setc2 - setc1:")
print(r2)
setn1 = set([1, 1, 2, 3, 4, 5])
setn2 = set([1, 5, 6, 7, 8, 9])
print("\nOriginal sets:")
print(setn1)
print(setn2)
r1 = setn1 - setn2
print("\nDifference of setn1 - setn2:")
print(r1)
r2 = setn2 - setn1
print("\nDifference of setn2 - setn1:")
print(r2)

Sample Output:

Original sets:
{'blue', 'green'}
{'yellow', 'blue'}

Difference of setc1 - setc2:
{'green'}

Difference of setc2 - setc1:
{'yellow'}

Original sets:
{1, 2, 3, 4, 5}
{1, 5, 6, 7, 8, 9}

Difference of setn1 - setn2:
{2, 3, 4}

Difference of setn2 - setn1:
{8, 9, 6, 7}

Visualize Python code execution:

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


Sample Solution-3:

Multiple sets in the difference() method

Python Code:

setn1 = set([1, 1, 2, 3, 4, 5])
setn2 = set([1, 5, 6, 7, 8, 9])
setn3 = set([3, 4, 5, 3, 9, 10])
setn4 = set([5, 7, 9, 10, 12, 14])
print("\nOriginal sets:")
print(setn1)
print(setn2)
print(setn3)
print(setn4)
print("\nDifference of setn1 - setn2,setn3,setn4:")
r1 = setn1.difference(setn2,setn3,setn4)
print(r1)
print("\nDifference of setn4 - setn1,setn2,setn3:")
r2 = setn4.difference(setn1,setn2,setn3)
print(r2)

Sample Output:

Original sets:
{1, 2, 3, 4, 5}
{1, 5, 6, 7, 8, 9}
{3, 4, 5, 9, 10}
{5, 7, 9, 10, 12, 14}

Difference of setn1 - setn2,setn3,setn4:
{2}

Difference of setn4 - setn1,setn2,setn3:
{12, 14}

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

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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