[英]Multi-objective optimisation using PyGMO
I am using the PyGMO package for Python, for multi-objective optimisation. 我正在使用用于Python的PyGMO软件包进行多目标优化。 I am unable to fix the dimension of the fitness function in the constructor, and the documentation is not very descriptive either.
我无法在构造函数中固定适应函数的尺寸,并且文档也不是非常描述性的。 I am wondering if anyone here has had experience with PyGMO in the past: this could be fairly simple.
我想知道这里是否有人曾经有过PyGMO的经验:这可能很简单。
I try to construct a minimum example below: 我尝试在下面构造一个最小示例:
from PyGMO.problem import base
from PyGMO import algorithm, population
import numpy as np
import matplotlib.pyplot as plt
class my_problem(base):
def __init__(self, fdim=2):
NUM_PARAMS = 4
super(my_problem, self).__init__(NUM_PARAMS)
self.set_bounds(0.01, 100)
def _objfun_impl(self, K):
E1 = K[0] + K[2]
E2 = K[1] + K[3]
return (E1, E2, )
if __name__ == '__main__':
prob = my_problem() # Create the problem
print (prob)
algo = algorithm.sms_emoa(gen=100)
pop = population(prob, 50)
pop = algo.evolve(pop)
F = np.array([ind.cur_f for ind in pop]).T
plt.scatter(F[0], F[1])
plt.xlabel("$E_1$")
plt.ylabel("$E_2$")
plt.show()
fdim=2
above is a failed attempt to set the fitness dimension. 上面的
fdim=2
设置健身度失败。 The code fails with the following error: 代码失败,并出现以下错误:
ValueError: ..\..\src\problem\base.cpp,584: fitness dimension was changed inside objfun_impl().
I'd be grateful if someone can help figure this out. 如果有人可以帮助我解决我,我将不胜感激。 Thanks!
谢谢!
Are you looking at the correct documentation ? 您在寻找正确的文档吗?
There is no fdim
(which anyway does nothing in your example since it is only a local variable and is not used). 没有
fdim
(在您的示例中它什么也不做,因为它只是一个局部变量而未使用)。 But there is n_obj
: 但是有
n_obj
:
n_obj: number of objectives.
n_obj:目标数。 Defaults to 1
默认为1
So, I think you want something like (corrected thanks to @Distopia): 因此,我认为您需要以下内容(通过@Distopia进行了更正):
#(...)
def __init__(self, fdim=2):
NUM_PARAMS = 4
super(my_problem, self).__init__(NUM_PARAMS, 0, fdim)
self.set_bounds(0.01, 100)
#(...)
I modified their example and this seemed to work for me. 我修改了他们的示例,这似乎对我有用。
#(...)
def __init__(self, fdim=2):
NUM_PARAMS = 4
# We call the base constructor as 'dim' dimensional problem, with 0 integer parts and 2 objectives.
super(my_problem, self).__init__(NUM_PARAMS,0,fdim)
self.set_bounds(0.01, 100)
#(...)
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