CODEWITHSUNDEEP
pythonnumpyrandomconditional-statementsgenerator
Tyr
Tyr

Reputation: 610

Conditional random number generator python numpy

I want to create a random number generator but with condition.

code is like below;

s_weights = []
num = 3
limit = 50000
np.random.seed(101)

for x in range(limit):
    weights = np.random.random(num)
    weights /= np.sum(weights)
    s_weights.append(weights)

it returns me 50.000 lists of numpy array of 3 weights (3,) like below

0.429134083359603413e-01 5.115615408184341906e-01 2.552505084560561729e-02

I want to limit first weight with rule of >=0.60

first weight should change between 0.60 - 1.00 and other two should change between 0.00 - 1.00

how can I modify the code?

thanks in advance

Upvotes: 1

Views: 1390

Answers (1)

Pedro Borges
Pedro Borges

Reputation: 1270

You can scale the first weight and then generate the other weights to respect the restriction of summing to 1. The updated code is below:

import numpy as np
s_weights = []
num = 3
limit = 50000
np.random.seed(101)
offset = 0.6

for x in range(limit):
    # By default all the weights go from 0 to 1
    weights = np.random.random(num)
    # shift and scale the first one to go from 0.6 to 1
    # in the case offset is 0.6 then it is x*0.4 + 0.6, which for 0 in 0 to 1 always falls in 0.6 to 1
    weights[0] = weights[0]*(1-offset) + offset 
    # Scales the second weight respecting that the sum must be 1
    second_max = 1-weights[0]
    weights[1] = weights[1]*second_max
    # third component should be equal to the value we need to complete 1
    weights[2] = 1-weights[0]-weights[1]
    s_weights.append(weights)
print(weights)
print(sum(weights))

an example output of a set of weights their sum is below

[0.84739308 0.11863514 0.03397177]
1.0

Upvotes: 1

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