RBFSampler¶
Extracts random features which approximate an RBF kernel.
This is a powerful way to give non-linear capacity to linear classifiers. This method is also called "random Fourier features" in the literature.
Parameters¶
-
gamma – defaults to
1.0RBF kernel parameter in
(-gamma * x^2). -
n_components – defaults to
100Number of samples per original feature. Equals the dimensionality of the computed feature space.
-
seed (int) – defaults to
NoneRandom number seed.
Examples¶
>>> from river import feature_extraction as fx
>>> from river import linear_model as lm
>>> from river import optim
>>> from river import stream
>>> # XOR function
>>> X = [[0, 0], [1, 1], [1, 0], [0, 1]]
>>> Y = [0, 0, 1, 1]
>>> model = lm.LogisticRegression(optimizer=optim.SGD(.1))
>>> for x, y in stream.iter_array(X, Y):
... model = model.learn_one(x, y)
... y_pred = model.predict_one(x)
... print(y, int(y_pred))
0 0
0 0
1 0
1 1
>>> model = (
... fx.RBFSampler(seed=3) |
... lm.LogisticRegression(optimizer=optim.SGD(.1))
... )
>>> for x, y in stream.iter_array(X, Y):
... model = model.learn_one(x, y)
... y_pred = model.predict_one(x)
... print(y, int(y_pred))
0 0
0 0
1 1
1 1
Methods¶
clone
Return a fresh estimator with the same parameters.
The clone has the same parameters but has not been updated with any data. This works by looking at the parameters from the class signature. Each parameter is either - recursively cloned if it's a River classes. - deep-copied via copy.deepcopy if not. If the calling object is stochastic (i.e. it accepts a seed parameter) and has not been seeded, then the clone will not be idempotent. Indeed, this method's purpose if simply to return a new instance with the same input parameters.
learn_one
Update with a set of features x.
A lot of transformers don't actually have to do anything during the learn_one step because they are stateless. For this reason the default behavior of this function is to do nothing. Transformers that however do something during the learn_one can override this method.
Parameters
- x (dict)
- kwargs
Returns
Transformer: self
transform_one
Transform a set of features x.
Parameters
- x (dict)
- y – defaults to
None
Returns
dict: The transformed values.