union method in python code example

Example 1: python union find

class DisjointSet:
    def __init__(self, n):
        self.data = list(range(n))
        self.size = n

    def find(self, index):
        return self.data[index]


	def union(self, x, y):
    	x, y = self.find(x), self.find(y)

	    if x == y:
    	    return

	    for i in range(self.size):
    	    if self.find(i) == y:
        	    self.data[i] = x


    @property
    def length(self):
        return len(set(self.data))




disjoint = DisjointSet(10)

disjoint.union(0, 1)
disjoint.union(1, 2)
disjoint.union(2, 3)
disjoint.union(4, 5)
disjoint.union(5, 6)
disjoint.union(6, 7)
disjoint.union(8, 9)

print(disjoint.data)
print(disjoint.length)


# [0, 0, 0, 0, 4, 4, 4, 4, 8, 8]
# 3

Example 2: list union python

set1 = {2, 4, 5, 6}  
set2 = {4, 6, 7, 8}  
set3 = {7, 8, 9, 10} 
  
# union of two sets 
print("set1 U set2 : ", set1.union(set2)) 
  
# union of three sets 
print("set1 U set2 U set3 :", set1.union(set2, set3)) 


>>>

set1 U set2 :  {2, 4, 5, 6, 7, 8}
set1 U set2 U set3 : {2, 4, 5, 6, 7, 8, 9, 10}

Example 3: .union in python

set1 = {2, 4, 5, 6}  
set2 = {4, 6, 7, 8}  
set3 = {7, 8, 9, 10} 
  
# union of two sets 
print("set1 U set2 : ", set1.union(set2)) 
  
# union of three sets 
print("set1 U set2 U set3 :", set1.union(set2, set3))