Why can't I change the values of a list in the class using a method?

I'm trying to implement simple Quick Find algorithm using python. This is the first time I am using OOP in Python. Following are the steps I took:

Create the class with init method so that it accepts N no. of elements for the list - "id", and I append the 0 - N-1 elements to the list.
```
class QuickFindUF:
   def __init__(self, N):
   self.id = []
   for i in range(N):
       self.id.append(i)
```

I create a union method which accepts the arguments: p & q(these are the values that I want to connect) and then change the list values so that the list items which have pid are changed to qid.

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:  # This part is getting ignored, I think.
        self.id[i] == qid

I create get_id method to see the changes in the id.
```
def get_id(self):
    return self.id
```

Now in the main part I do this to see the results:

if __name__ == "__main__":

qf = QuickFindUF(5)
print(qf.get_id())
qf.union(0, 3)
print(qf.get_id())

I should see the updated id[] after I call the union method but id doesn't change.
Expected output:[0, 1, 2, 3, 4] [3, 1, 2, 3, 4]
Actual output: [0, 1, 2, 3, 4] [0, 1, 2, 3, 4]

I tried to change some values of id manually without using the "if" statement in union method and that worked out fine, like: id[0] = 'a' and that worked out fine: the output was: [0, 1, 2, 3, 4] ['a', 1, 2, 3, 4]

So why is the union method not working if I use a for loop with if statements to change the values of the list?

I also tried returning the id[] in the union() like this:
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:  # This part is getting ignored, I think.
        self.id[i] == qid```

But I get the same output when I print(qf.union())

Solution

Try this

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:  # This part is getting ignored, I think.
            self.id[i] = qid