Why are random generated sequences of numbers the same for different class instances?

Question

I've been trying to generate different dictionary structures (pertaining to different class instances in Python) filled with random number values between [0, 1). The keys of the dictionary are not that the important. But, the main problem is that when I try and generate the dictionaries with the random values, they all come up as the same sequence:

{'p0': 0.8834439890229875, 'p1': 0.4542011548977558, 'd0': 0.041855079212439805, 'c0': 0.30179244567633823, 'c1': 0.026356543619428408, 'c2': 0.24603169392476631}
{'p0': 0.8834439890229875, 'p1': 0.4542011548977558, 'd0': 0.041855079212439805, 'c0': 0.30179244567633823, 'c1': 0.026356543619428408, 'c2': 0.24603169392476631}
{'p0': 0.8834439890229875, 'p1': 0.4542011548977558, 'd0': 0.041855079212439805, 'c0': 0.30179244567633823, 'c1': 0.026356543619428408, 'c2': 0.24603169392476631}

Code:

''' Individual Class '''

from random import Random

class Individual:

        chromosome = {} #The chromosome of an individual is a random generated dictionary.
        randomInstance = Random(datetime.now())

        def __init__(self, numP, numD, numC):
                self.randomInstance.seed()
                for i in range(numP):
                        plant = "p"
                        plant += str(i)
                        self.chromosome[plant] = self.randomInstance.random()

                for j in range(numD):
                        plant = "d"
                        plant += str(j)
                        self.chromosome[plant] = self.randomInstance.random()

                for k in range(numC):
                        plant = "c"
                        plant += str(k)
                        self.chromosome[plant] = self.randomInstance.random()

def main():

        list = []
        for i in range(4):
                inst = Individual(2, 1 ,3)
                list.append(inst.chromosome)

        print(list)

I'm trying to get a different sequence per class instance.

Hope someone can help. Thank you all.

Don’t name a variable `list`. Also I’m pretty sure they’re all sharing the same seed, which is why you get the same exact numbers. — AMC, Dec 12 '19 at 20:02
@snakecharmerb That question has the exact same naming mistake too lol — AMC, Dec 12 '19 at 20:04

score 0 · Accepted Answer · answered Dec 12 '19 at 20:07

0

You're declaring chromosome and randomInstance as class attributes so they're shared across all instances of the class. If you want it per instance then initialize them as class properties in the init instead.

answered Dec 12 '19 at 20:07

Philippe Dixon

87
3

Thank you, that was the issue. Cheers. – Albert E Dec 12 '19 at 20:21

Why are random generated sequences of numbers the same for different class instances?

1 Answers1