CODEWITHSUNDEEP
pythonrecursioncopy
Nelly
Nelly

Reputation: 309

Python: maximum recursion depth exceeded while calling a Python object when calling copy function

I have a class Particle which has some parameters and attributes, as you can see below. But, when it does get to the function setter for position, and it executes the copy() function, I get the error message : RuntimeError: maximum recursion depth exceeded while calling a Python object. I've tried different options, like deepcopy(), or import sys sys.setrecursionlimit(10000) , but none of them worked... Does anyone have any idea? This is my code:

def initCost(n):
    a = random.randint(0,10)              #gram.
    b = random.randint(0,5)             #price
    return [random.randint(0,a*b) for i in range(n)]

costs = initCost(10)

class Particle:
    def __init__(self, n, maxWeight):
        self.position = [random.randint(0,1) for i in range(n)]  #position
        self.velocity = [0 for i in range(n)]                    #velocity
        #self.fit = self.fitness(self.position)
        self.bp = self.position.copy()                           #best position
        self.bf = self.fit                                 #best fitness
        self.evaluate()

    def fit(self, x):
        fitt = 0
        for i in range(len(x)-1):
            if (x[i] == 1):
                fitt = fitt + costs[i]
        return fitt

    def evaluate(self):
        """ evaluates the particle """
        self.fitness = self.fit(self.position)

    @property
    def position(self):
        return self.position

    @property
    def bp(self):
        return self.bp

    @property
    def bf(self):
        return self.bf

    @position.setter
    def position(self, newPosition):
        self.position = newPosition.copy()
        #self.position = newPosition[:]
        self.evaluate()
        # automatic update of particle's memory
        if (self.fit<self.bf):
            self.bp = self.position
            self.bf  = self.fit

Upvotes: 3

Views: 5093

Answers (1)

user2357112
user2357112

Reputation: 280993

It looks like you're trying to use position as the name of both the property and the ordinary attribute backing it. For example,

@position.setter
def position(self, newPosition):
    self.position = newPosition.copy()
#   ^^^^^^^^^^^^^^^

This attempt to set self.position will use the setter you're defining! Similarly,

@property
def position(self):
    return self.position

This getter just calls itself!

Trying to use self.position inside the position property definition won't bypass the property. If you want a "regular" attribute backing the property, call it something else, like self._position or something.

Upvotes: 4

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