Noises

Olympus provides a way to inject noise explicitly into the benchmarks. At the moment, only adding noise to the output of the Surfaces is supported.

Noise objects can be accessed by importing the specific noise class from the olympus.noises module, or via the Noise function. For instance, to load an object that injects Gaussian noise, you can use the Noise function:

from olympus import Noise
noise = Noise(kind='GaussianNoise', scale=1.2)

The above is equivalent to importing the class GaussianNoise directly:

from olympus.noises import GaussianNoise
noise = GaussianNoise(scale=1.2)

This latter approach, however, allows for more control over the details of the noise object. For instance, the Gamma-distributed noise also allows to set a lower bound for its support that is different from zero:

from olympus.noises import GammaNoise
noise = GammaNoise(scale=1, lower_bound=-5)

Once a noise instance is defined as above, it can be passed to one of the Surfaces to enable obtaining noisy evaluations:

from olympus.surfaces import HyperEllipsoid
from olympus.noises import GaussianNoise

noise = GaussianNoise(scale=2)
noisy_surface = HyperEllipsoid(param_dim=1, noise=noise)

# evaluate the same location three times
for i in range(3):
    print(noisy_surface.run(0.5))

>>> [[0.7303638140484728]]
>>> [[0.6398992941066822]]
>>> [[0.29602882702845845]]

If you wanted to define your own, customized noise class, you can do it as follows by inheriting from the AbstractNoise class:

from olympus.noises import AbstractNoise

class CustomNoise(AbstractNoise):

    def __init__(self, scale=1):
        AbstractNoise.__init__(**locals())

    def _add_noise(self, value):
        # ----------------------------------------------
        # Here you define the noise as you desire, e.g.:
        # ----------------------------------------------
        if value > 2:
            noisy_value = value + self.scale
        else:
            noisy_value = value - self.scale

        return noisy_value

Noise Classes

These are the types of noise currently available in Olympus.

• GaussianNoise
• UniformNoise
• GammaNoise

Noise Function

olympus.noises.Noise(kind='GaussianNoise', scale=1)

Convenience function to access noise objects. It returns a certain noise object with defaults arguments.

Parameters

kind (str or AbstractNoise) – Keyword identifying one of the noise objects available in Olympus. Alternatively, you can pass a custom noise class that is a subclass of AbstractNoise.

Returns

An instance of the chosen noise.

Return type

Noise (object)