embarrassingly

Embarrassingly obvious (in retrospect) ways to hack objective functions before you send them to optimization routines.

Install

pip install embarrassingly 

Example 1 : Parallel objective computation

from embarrassingly.parallel import Parallel
import optuna

def pre_objective(worker, trial):
    print('Hi this is worker ' + str(worker))
    x = [trial.suggest_float('x' + str(i), 0, 1) for i in range(3)]
    return x[0] + x[1] * x[2]

def test_optuna():
    objective = Parallel(pre_objective, num_workers=7)
    study = optuna.create_study()
    study.optimize(objective, n_trials=15, n_jobs=7)

Example 2 : Plateau finding

from embarrassingly.cautious import Underpromoted
import numpy as np
import math
from scipy.optimize import shgo

def plateaudinous(x):
""" A helicopter landing pad when you turn it upside down """
r = np.linalg.norm(x)
x0 = np.array([0.25,0.25])
amp = r*math.sin(16*r*r)
return -1 if np.linalg.norm(x-x0)<0.1 else 0.1*x[0] + amp

bounds = [(-1,1),(-1,1)]
res1 = shgo(func=plateaudinous, bounds=bounds, n=8, iters=4, options={'minimize_every_iter': True, 'ftol': 0.1})
print("Global min occurs at "+str(res1.x))

# But let's land our helicopter in the flat spot! 
platypus = Underpromoted(plateaudinous, bounds=bounds, radius=0.01)
res2 = shgo(func=platypus, bounds=bounds, n=8, iters=4, options={'minimize_every_iter': True, 'ftol': 0.1})
print('Helicopter lands at '+str(res2.x))

Example 3 : Expensive functions

def slow_and_pointless(x):
""" Example of a function with varying computation time """
    r = np.linalg.norm(x)
    quad = (0.5*0.5-r*r)/(0.5*0.5)
    compute_time = max(0,0.5*quad+x[0])
    time.sleep(compute_time)
    return schwefel([1000*x[0],980*x[1]])[0]

# Save time by making it a "shy" objective function
bounds = [(-0.5, 0.5), (-0.5, 0.5)]
SAP = Shy(slow_and_pointless, bounds=bounds, t_unit=0.01, d_unit=0.3)
from scipy.optimize import minimize
res = scipy.optimize.shgo(func=SAP, bounds=bounds, n=8, iters=4, options={'minimize_every_iter': True, 'ftol': 0.1})

Built With

• python