def fast_knn(X,
n_clusters=5,
n_neighbors=None,
graph_mode='distance',
cluster_mode='spectral',
algorithm='brute',
n_jobs=1,
random_state=1234,
force_sklearn=False):
r"""
Arguments:
X : `ndarray` or tuple of (X, y)
n_neighbors: int (default = 5)
The top K closest datapoints you want the algorithm to return.
Currently, this value must be < 1024.
graph_mode : {'distance', 'connectivity'}, default='distance'
This mode decides which values `kneighbors_graph` will return:
- 'connectivity' : will return the connectivity matrix with ones and
zeros (for 'SpectralClustering').
- 'distance' : will return the distances between neighbors according
to the given metric (for 'DBSCAN').
cluster_mode: {'vote', 'spectral', 'isomap'}, default='vote'
This mode decides how to generate cluster prediction from the
neighbors graph:
- 'dbscan' :
- 'spectral' :
- 'isomap' :
- 'kmeans' :
algorithm : {'auto', 'ball_tree', 'kd_tree', 'brute'}, optional
Algorithm used to compute the nearest neighbors:
- 'ball_tree' will use :class:`BallTree`
- 'kd_tree' will use :class:`KDTree`
- 'brute' will use a brute-force search.
- 'auto' will attempt to decide the most appropriate algorithm
based on the values passed to :meth:`fit` method.
Note: fitting on sparse input will override the setting of
this parameter, using brute force.
"""
kwargs = dict(locals())
X = kwargs.pop('X')
force_sklearn = kwargs.pop('force_sklearn')
random_state = kwargs.pop('random_state')
n_clusters = int(kwargs.pop('n_clusters'))
if n_neighbors is None:
kwargs['n_neighbors'] = n_clusters
n_neighbors = n_clusters
## graph mode
graph_mode = str(kwargs.pop('graph_mode')).strip().lower()
assert graph_mode in ('distance', 'connectivity')
## cluster mode
cluster_mode = str(kwargs.pop('cluster_mode')).strip().lower()
## fine-tuning the kwargs
use_cuml = _check_cuml(force_sklearn)
if use_cuml:
from cuml.neighbors import NearestNeighbors
kwargs['n_gpus'] = kwargs['n_jobs']
kwargs.pop('n_jobs')
kwargs.pop('algorithm')
else:
from sklearn.neighbors import NearestNeighbors
## fitting
knn = NearestNeighbors(**kwargs)
knn.fit(X)
knn._fitid = id(X)
## Transform mode
knn._random_state = random_state
knn._n_clusters = n_clusters
knn._graph_mode = graph_mode
knn._cluster_mode = cluster_mode
if use_cuml:
knn.n_samples_fit_ = X.shape[0]
knn.kneighbors_graph = types.MethodType(nn_kneighbors_graph, knn)
knn.transform = types.MethodType(nn_transform, knn)
knn.fit_transform = types.MethodType(nn_fit_transform, knn)
knn.predict = types.MethodType(nn_predict, knn)
return knn
