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class sklearn.model_selection.ParameterSampler(param_distributions, n_iter, random_state=None)
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Generator on parameters sampled from given distributions.
Non-deterministic iterable over random candidate combinations for hyper- parameter search. If all parameters are presented as a list, sampling without replacement is performed. If at least one parameter is given as a distribution, sampling with replacement is used. It is highly recommended to use continuous distributions for continuous parameters.
Note that before SciPy 0.16, the
scipy.stats.distributions
do not accept a custom RNG instance and always use the singleton RNG fromnumpy.random
. Hence settingrandom_state
will not guarantee a deterministic iteration wheneverscipy.stats
distributions are used to define the parameter search space. Deterministic behavior is however guaranteed from SciPy 0.16 onwards.Read more in the User Guide.
Parameters: param_distributions : dict
Dictionary where the keys are parameters and values are distributions from which a parameter is to be sampled. Distributions either have to provide a
rvs
function to sample from them, or can be given as a list of values, where a uniform distribution is assumed.n_iter : integer
Number of parameter settings that are produced.
random_state : int or RandomState
Pseudo random number generator state used for random uniform sampling from lists of possible values instead of scipy.stats distributions.
Returns: params : dict of string to any
Yields dictionaries mapping each estimator parameter to as sampled value.
Examples
>>> from sklearn.model_selection import ParameterSampler >>> from scipy.stats.distributions import expon >>> import numpy as np >>> np.random.seed(0) >>> param_grid = {'a':[1, 2], 'b': expon()} >>> param_list = list(ParameterSampler(param_grid, n_iter=4)) >>> rounded_list = [dict((k, round(v, 6)) for (k, v) in d.items()) ... for d in param_list] >>> rounded_list == [{'b': 0.89856, 'a': 1}, ... {'b': 0.923223, 'a': 1}, ... {'b': 1.878964, 'a': 2}, ... {'b': 1.038159, 'a': 2}] True .. automethod:: __init__
model_selection.ParameterSampler()
2017-01-15 04:24:16
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