Question

I’m learning Python OOP and trying to convert a Java class to a Python class

See page 15 in this PDF for Java code google doc link

class QuickFindUF:
        """docstring for QuickFindUF"""


    def __init__(self, n):
            self.id = []
            for e in range(n):
                    self.id.append(e)


    def connected(self,p,q):
            return self.id[p]==self.id[q]

    def union(self,p,q):
            self.pid = self.id[p]
            self.qid = self.id[q]
            for i in range(len(self.id)):
                    if(self.id[i]==self.pid):
                            self.id[i]=self.qid


quf = QuickFindUF(9)
quf.union(3,4)
print quf.connected(3,4)

There are 16 self keywords in this class. Is there a better way to write this class?

Answer 1

Yea, you don’t want to assign these variables to self, these are local variables:

def union(self,p,q):
        self.pid = self.id[p]
        self.qid = self.id[q]
        for i in range(len(self.id)):
                if(self.id[i]==self.pid):
                        self.id[i]=self.qid

Should be:

def union(self,p,q):
    pid = self.id[p]
    qid = self.id[q]
    for i in range(len(self.id)):
        if self.id[i] == pid:
            self.id[i] = qid

You only use self when referring to instance variables, not to any variable inside of a method.