Mixed¶
Mixed data stream generator.
This generator is an implementation of a data stream with abrupt concept drift and boolean noise-free examples as described in 1.
It has four relevant attributes, two boolean attributes \(v, w\) and two numeric attributes \(x, y\) uniformly distributed from 0 to 1. The examples are labeled depending on the classification function chosen from below.
-
function 0
: if \(v\) and \(w\) are true or \(v\) and \(z\) are true or \(w\) and \(z\) are true then 0 else 1, where \(z\) is \(y < 0.5 + 0.3 sin(3 \pi x)\) -
function 1
: The opposite offunction 0
.
Concept drift can be introduced by changing the classification function. This can be done manually or using ConceptDriftStream
.
Parameters¶
-
classification_function (int) – defaults to
0
Which of the two classification functions to use for the generation. Valid options are 0 or 1.
-
seed (int) – defaults to
None
If int,
seed
is used to seed the random number generator; If RandomState instance,seed
is the random number generator; If None, the random number generator is theRandomState
instance used bynp.random
. -
balance_classes (bool) – defaults to
False
Whether to balance classes or not. If balanced, the class distribution will converge to a uniform distribution.
Attributes¶
-
desc
Return the description from the docstring.
Examples¶
>>> from river import synth
>>>
>>> dataset = synth.Mixed(seed = 42, classification_function=1, balance_classes = True)
>>>
>>> for x, y in dataset.take(5):
... print(x, y)
{0: False, 1: True, 2: 0.7319, 3: 0.5986} 1
{0: False, 1: False, 2: 0.0580, 3: 0.8661} 0
{0: True, 1: True, 2: 0.0205, 3: 0.9699} 1
{0: False, 1: True, 2: 0.4319, 3: 0.2912} 0
{0: True, 1: False, 2: 0.2921, 3: 0.3663} 1
Methods¶
generate_drift
Generate drift by switching the classification function.
take
Iterate over the k samples.
Parameters
- k (int)
Notes¶
The sample generation works as follows: The two numeric attributes are generated with the random generator initialized with the seed passed by the user (optional). The boolean attributes are either 0 or 1 based on the comparison of the random number generator and 0.5 , the classification function decides whether to classify the instance as class 0 or class 1. The next step is to verify if the classes should be balanced, and if so, balance the classes.
The generated sample will have 4 relevant features and 1 label (it is a binary-classification task).
References¶
-
Gama, Joao, et al. "Learning with drift detection." Advances in artificial intelligence–SBIA 2004. Springer Berlin Heidelberg, 2004. 286-295" ↩