Binarize data (set feature values to 0 or 1) according to a threshold
Values greater than the threshold map to 1, while values less than or equal to the threshold map to 0. With the default threshold of 0, only positive values map to 1.
Binarization is a common operation on text count data where the analyst can decide to only consider the presence or absence of a feature rather than a quantified number of occurrences for instance.
It can also be used as a pre-processing step for estimators that consider boolean random variables (e.g. modelled using the Bernoulli distribution in a Bayesian setting).
Read more in the :ref:`User Guide <preprocessing_binarization>`.
Parameters ---------- threshold : float, optional (0.0 by default) Feature values below or equal to this are replaced by 0, above it by 1. Threshold may not be less than 0 for operations on sparse matrices.
copy : boolean, optional, default True set to False to perform inplace binarization and avoid a copy (if the input is already a numpy array or a scipy.sparse CSR matrix).
Examples -------- >>> from sklearn.preprocessing import Binarizer >>> X = [ 1., -1., 2.],
... [ 2., 0., 0.],
... [ 0., 1., -1.]
>>> transformer = Binarizer().fit(X) # fit does nothing. >>> transformer Binarizer() >>> transformer.transform(X) array([1., 0., 1.],
[1., 0., 0.],
[0., 1., 0.]
)
Notes ----- If the input is a sparse matrix, only the non-zero values are subject to update by the Binarizer class.
This estimator is stateless (besides constructor parameters), the fit method does nothing but is useful when used in a pipeline.
See also -------- binarize: Equivalent function without the estimator API.