Passing values from different classes in python

Question

I am new to the python programming. I met a problem now that I want to call some results from one class to another class as one of the __init__ attributes. Here is the code shown below: (reduced_data is numerical data in vector)

class A:
    def __init__(self, k=3, tol=0.0001, max_iter=300):
        self.k = k
        self.tol = tol
        self.max_iter = max_iter

    def fit(self, data):

        self.centroids = {}

        for i in range(self.k):
            self.centroids[i] = data[i+50]

        for i in range(self.max_iter):
            self.classifications = {}

            for i in range(self.k):
                self.classifications[i] = []

            for featureset in data:
                distances = [np.linalg.norm(featureset - self.centroids[centroid]) for centroid in self.centroids]
                classification = distances.index(min(distances))
                self.classifications[classification].append(featureset)
            prev_centroids = dict(self.centroids)

            for classification in self.classifications:
                self.centroids[classification] = np.average(self.classifications[classification], axis=0)

            optimized = True

            for c in self.centroids:
                original_centroid = prev_centroids[c]
                current_centroid = self.centroids[c]
                if np.sum((current_centroid - original_centroid) / original_centroid * 100.0) > self.tol:
                    #print(np.sum((current_centroid - original_centroid) / original_centroid * 100.0))
                    optimized = False

            if optimized:
                break
            
    def cluster_labels(self,data):
        cluster_labels = []
        for featureset in data:
            distances=[np.linalg.norm(featureset - self.centroids[centroid]) for centroid in self.centroids]
            cluster_labels.append(distances.index(min(distances)))
        return cluster_labels

class B:
        x = np.linalg.norm(reduced_data-[1,1])
        k = (x-5)^2
        a = A()
        a.fit(reduced_data)
        y_pred = a.predict(reduced_data)
        labels = a.cluster_labels(reduced_data)

Basically, I want to pass the value k in class B as the attribute of class A in def __init__(self, k=k in class B, tol=0.0001, max_iter=300):And how could I achieve it?

John Ladasky · Accepted Answer · 2020-09-15 08:32:54Z

1

Quick answer: change the third line in class B to: a = A(k=k).

But ask yourself a more fundamental question. Why is "class B" a class at all? As you have written it, it doesn't have any "self" properties, so it has no preserved state. You calculate y_pred and labels exactly once. These are class attributes. After that, they never change. I suggest that you just eliminate the class and place the last six lines in the main body of your code.

answered Sep 15, 2020 at 8:32

John Ladasky

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b9s · Accepted Answer · 2020-09-15 08:27:05Z

1

You can pass the parameters from the __init__ method when creating a new instance of that object.

I.e. a = A(k).

Note that in class B, the code is not inside a method. You may want to put that code outside of the class definition. In Python, code doesn't have to inside a class.

answered Sep 15, 2020 at 8:27

b9s

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go2nirvana · Accepted Answer · 2020-09-15 08:34:25Z

0

Your class A doesn't have the attribute k, however it's instance does.

So you either should make k a class attribute of A or pass the value of instance of A.k to B each time.

answered Sep 15, 2020 at 8:34

go2nirvana

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