# Source code for divik.cluster._divik._sklearn

```
import sys
from functools import partial
from typing import Optional, Tuple
import numpy as np
import pandas as pd
import tqdm
from scipy.spatial import distance as dist
from sklearn.base import (
BaseEstimator,
ClusterMixin,
TransformerMixin,
)
from sklearn.utils.validation import check_is_fitted
from divik import _summary as summary
from divik import feature_selection as fs
from divik.core import (
DivikResult,
configurable,
context_if,
maybe_pool,
normalize_rows,
visualize,
)
from divik.core.io import saver
from ._backend import divik
from ._report import DivikReporter
[docs]@configurable
class DiviK(BaseEstimator, ClusterMixin, TransformerMixin):
"""DiviK clustering
Parameters
----------
kmeans: AutoKMeans
A self-tuning KMeans estimator for the purpose of clustering.
Two implementations are provided in `divik.cluster` package:
`DunnSearch` and `GAPSearch`.
fast_kmeans: GAPSearch, optional, default: None
A self-tuning KMeans estimator for the purpose of stop condition
check. If None, the `kmeans` parameter is assumed to be the
`GAPSearch` instance.
distance: str, optional, default: 'correlation'
The distance metric between points, centroids and for GAP index
estimation. One of the distances supported by scipy package.
minimal_size: int or float, optional, default: None
The minimum size of the region (the number of observations) to be
considered for any further divisions. If provided number is between
0 and 1, it is considered a rate of training dataset size. When left
None, defaults to 0.1% of the training dataset size.
rejection_size: int, optional, default: None
Size under which split will be rejected - if a cluster appears in the
split that is below rejection_size, the split is considered improper
and discarded. This may be useful for some domains (like there is no
justification for a 3-cells cluster in biological data). By default,
no segmentation is discarded, as careful post-processing provides the
same advantage.
rejection_percentage: float, optional, default: None
An alternative to ``rejection_size``, with the same behavior, but this
parameter is related to the training data size percentage. By default,
no segmentation is discarded.
minimal_features_percentage: float, optional, default: 0.01
The minimal percentage of features that must be preserved after
GMM-based feature selection. By default at least 1% of features is
preserved in the filtration process.
features_percentage: float, optional, default: 0.05
The target percentage of features that are used by fallback percentage
filter for 'outlier' filter.
normalize_rows: bool, optional, default: None
Whether to normalize each row of the data to the norm of 1. By default,
it normalizes rows for correlation metric, does no normalization
otherwise.
neutral: float, optional, default: None
Element skipped when filtering.
use_logfilters: bool, optional, default: False
Whether to compute logarithm of feature characteristic instead of the
characteristic itself. This may improve feature filtering performance,
depending on the distribution of features, however all the
characteristics (mean, variance) have to be positive for that -
filtering will fail otherwise. This is useful for specific cases in
biology where the distribution of data may actually require this option
for any efficient filtering.
filter_type: {'gmm', 'outlier', 'auto', 'none'}, default: 'gmm'
- 'gmm' - usual Gaussian Mixture Model-based filtering, useful for high
dimensional cases
- 'outlier' - robust outlier detection-based filtering, useful for low
dimensional cases. In the case of no outliers, percentage-based
filtering is applied.
- 'auto' - automatically selects between 'gmm' and 'outlier' based on
the dimensionality. When more than 250 features are present, 'gmm'
is chosen.
- 'none' - feature selection is disabled
n_jobs: int, optional, default: None
The number of jobs to use for the computation. This works by computing
each of the GAP index evaluations in parallel and by making predictions
in parallel.
verbose: bool, optional, default: False
Whether to report the progress of the computations.
Attributes
----------
result_: divik.DivikResult
Hierarchical structure describing all the consecutive segmentations.
labels_:
Labels of each point
centroids_: array, [n_clusters, n_features]
Coordinates of cluster centers. If the algorithm stops before fully
converging, these will not be consistent with ``labels_``. Also, the
distance between points and respective centroids must be captured
in appropriate features subspace. This is realized by the ``transform``
method.
filters_: array, [n_clusters, n_features]
Filters that were applied to the feature space on the level that was
the final segmentation for a subset.
depth_: int
The number of hierarchy levels in the segmentation.
n_clusters_: int
The final number of clusters in the segmentation, on the tree leaf
level.
paths_: Dict[int, Tuple[int]]
Describes how the cluster number corresponds to the path in the tree.
Element of the tuple indicates the sub-segment number on each tree
level.
reverse_paths_: Dict[Tuple[int], int]
Describes how the path in the tree corresponds to the cluster number.
For more details see ``paths_``.
Examples
--------
>>> from divik.cluster import DiviK, DunnSearch, KMeans
>>> from sklearn.datasets import make_blobs
>>> X, _ = make_blobs(n_samples=1_000,
... n_features=2,
... centers=7,
... random_state=42,
... )
>>> divik = DiviK(
... kmeans=DunnSearch( # we want to use Dunn's method for finding the optimal number of clusters
... kmeans=KMeans(
... n_clusters=2, # it is required, like in scikit-learn, but you can provide any number here,
... # DunnSearch will override it anyway
... ),
... max_clusters=5, # for the sake of the example I'll keep it low
... ),
... minimal_size=100, # for the sake of the example, I won't split clusters with less than 100 elements
... filter_type='none', # we have 2 features in sample data, feature selection would be pointless
... ).fit(X)
>>> divik.n_clusters_
22
>>> divik.labels_
array([1, 1, 1, 0, ..., 0, 0], dtype=int32)
>>> divik.predict([[0, ..., 0], [12, ..., 3]])
array([1, 0], dtype=int32)
>>> divik.cluster_centers_
array([[10., ..., 2.],
...,
[ 1, ..., 2.]])
"""
def __init__(
self,
kmeans,
fast_kmeans=None,
distance: str = "correlation",
# TODO: Allow percentage
minimal_size: int = None,
rejection_size: int = None,
rejection_percentage: float = None,
minimal_features_percentage: float = 0.01,
features_percentage: float = 0.05,
normalize_rows: bool = None,
neutral: float = None,
use_logfilters: bool = False,
filter_type="gmm",
n_jobs: int = None,
verbose: bool = False,
):
self.kmeans = kmeans
self.fast_kmeans = fast_kmeans
self.distance = distance
self.minimal_size = minimal_size
self.rejection_size = rejection_size
self.rejection_percentage = rejection_percentage
self.minimal_features_percentage = minimal_features_percentage
self.features_percentage = features_percentage
self.normalize_rows = normalize_rows
self.neutral = neutral
self.use_logfilters = use_logfilters
self.filter_type = filter_type
self.n_jobs = n_jobs
self.verbose = verbose
self._validate_arguments()
def _validate_arguments(self):
if self.minimal_features_percentage < 0 or self.minimal_features_percentage > 1:
raise ValueError("minimal_features_percentage must be in range" " [0, 1]")
if self.features_percentage < 0 or self.features_percentage > 1:
raise ValueError("features_percentage must be in range [0, 1]")
if self.features_percentage < self.minimal_features_percentage:
raise ValueError(
"features_percentage must be higher than or equal"
" to minimal_features_percentage"
)
if self.filter_type not in ["gmm", "outlier", "auto", "none"]:
raise ValueError(
"filter_type must be in ['gmm', 'outlier', 'auto', 'none']"
)
[docs] def fit(self, X, y=None):
"""Compute DiviK clustering.
Parameters
----------
X : array-like or sparse matrix, shape=(n_samples, n_features)
Training instances to cluster. It must be noted that the data
will be converted to C ordering, which will cause a memory
copy if the given data is not C-contiguous.
y : Ignored
not used, present here for API consistency by convention.
"""
if np.isnan(X).any():
raise ValueError("NaN values are not supported.")
with context_if(
self.verbose, tqdm.tqdm, total=X.shape[0], file=sys.stdout, smoothing=0
) as progress:
self.result_ = self._divik(X, progress)
if self.result_ is None:
self.labels_ = np.zeros((X.shape[0],), dtype=int)
self.paths_ = {0: (0,)}
else:
self.labels_, self.paths_ = summary.merged_partition(
self.result_, return_paths=True
)
self.reverse_paths_ = {value: key for key, value in self.paths_.items()}
if self.result_ is None:
self.filters_ = np.ones([1, X.shape[1]], dtype=bool)
else:
self.filters_ = np.array(
[self._get_filter(path) for path in self.reverse_paths_], dtype=bool
)
self.centroids_ = pd.DataFrame(X).groupby(self.labels_, sort=True).mean().values
self.depth_ = summary.depth(self.result_)
self.n_clusters_ = summary.total_number_of_clusters(self.result_)
return self
def _get_rejection_size(self, X):
rejection_size = 0
if self.rejection_size is not None:
rejection_size = max(rejection_size, self.rejection_size)
if self.rejection_percentage is not None:
rejection_size = max(
rejection_size, int(self.rejection_percentage * X.shape[0])
)
return rejection_size
def _get_filter(self, path):
"""This method extracts features filter used for each centroid"""
result = self.result_
for item in path[:-1]:
result = result.subregions[item]
return result.feature_selector.selected_
def _needs_normalization(self):
if self.normalize_rows is None:
return self.distance == "correlation"
return self.normalize_rows
def _feature_selector(self, n_features):
return fs.make_specialized_selector(
self.filter_type,
n_features,
use_log=self.use_logfilters,
min_features_rate=self.minimal_features_percentage,
p=self.features_percentage,
neutral=self.neutral,
)
def _divik(self, X, progress):
full = self.kmeans
fast = self.fast_kmeans
warn_const = getattr(full.kmeans, "normalize_rows", False)
if fast is not None and not warn_const:
warn_const = getattr(fast.kmeans, "normalize_rows", False)
report = DivikReporter(progress, warn_const=warn_const)
select_all = np.ones(shape=(X.shape[0],), dtype=bool)
if self.minimal_size is None:
minimal_size = int(X.shape[0] * 0.001)
elif 0 < self.minimal_size < 1:
minimal_size = int(X.shape[0] * self.minimal_size)
else:
minimal_size = self.minimal_size
rejection_size = self._get_rejection_size(X)
return divik(
X,
selection=select_all,
kmeans=full,
fast_kmeans=fast,
feature_selector=self._feature_selector(X.shape[1]),
minimal_size=minimal_size,
rejection_size=rejection_size,
report=report,
)
[docs] def fit_predict(self, X, y=None):
"""Compute cluster centers and predict cluster index for each sample.
Convenience method; equivalent to calling fit(X) followed by
predict(X).
Parameters
----------
X : {array-like, sparse matrix}, shape = [n_samples, n_features]
New data to transform.
y : Ignored
not used, present here for API consistency by convention.
Returns
-------
labels : array, shape [n_samples,]
Index of the cluster each sample belongs to.
"""
return self.fit(X).labels_
[docs] def transform(self, X):
"""Transform X to a cluster-distance space.
In the new space, each dimension is the distance to the cluster
centers. Note that even if X is sparse, the array returned by
`transform` will typically be dense.
Parameters
----------
X : {array-like, sparse matrix}, shape = [n_samples, n_features]
New data to transform.
Returns
-------
X_new : array, shape [n_samples, self.n_clusters_]
X transformed in the new space.
"""
check_is_fitted(self)
if self._needs_normalization():
X = normalize_rows(X)
distances = np.hstack(
[
dist.cdist(
X[:, selector], centroid[np.newaxis, selector], self.distance
)
for selector, centroid in zip(self.filters_, self.centroids_)
]
)
return distances
[docs] def fit_transform(self, X, y=None, **fit_params):
"""Compute clustering and transform X to cluster-distance space.
Equivalent to fit(X).transform(X), but more efficiently implemented.
Parameters
----------
X : {array-like, sparse matrix}, shape = [n_samples, n_features]
New data to transform.
y : Ignored
not used, present here for API consistency by convention.
Returns
-------
X_new : array, shape [n_samples, self.n_clusters_]
X transformed in the new space.
"""
return self.fit(X).transform(X)
[docs] def predict(self, X):
"""Predict the closest cluster each sample in X belongs to.
In the vector quantization literature, `cluster_centers_` is called
the code book and each value returned by `predict` is the index of
the closest code in the code book.
Parameters
----------
X : {array-like, sparse matrix}, shape = [n_samples, n_features]
New data to predict.
Returns
-------
labels : array, shape [n_samples,]
Index of the cluster each sample belongs to.
"""
check_is_fitted(self)
if self._needs_normalization():
X = normalize_rows(X)
predict = partial(_predict_path, result=self.result_)
with maybe_pool(self.n_jobs) as pool:
paths = pool.map(predict, X)
labels = [self.reverse_paths_[path] for path in paths]
return np.array(labels, dtype=np.int32)
def _predict_path(observation: np.ndarray, result: DivikResult) -> Tuple[int]:
path = []
observation = observation[np.newaxis, :]
division = result
while division is not None:
local_X = division.feature_selector.transform(observation)
label = int(division.clustering.predict(local_X))
path.append(label)
division = division.subregions[label]
path = tuple(path) if len(path) else (0,)
return path
def make_merged(result: Optional[DivikResult]) -> np.ndarray:
depth = summary.depth(result)
return np.hstack(
[
summary.merged_partition(result, limit + 1).reshape(-1, 1)
for limit in range(depth)
]
)
def save_merged(fname_fn, merged: np.ndarray, xy: np.ndarray = None):
np.savetxt(fname_fn("partitions.csv"), merged, delimiter=", ", fmt="%i")
np.save(fname_fn("partitions.npy"), merged)
import skimage.io
if xy is not None:
for level in range(merged.shape[1]):
np.save(fname_fn("partitions.{0}.npy".format(level)), merged[:, level])
visualization = visualize(merged[:, level], xy=xy)
image_name = fname_fn("partitions.{0}.png".format(level))
skimage.io.imsave(image_name, visualization)
@saver
def save_divik(model, fname_fn, **kwargs):
if not hasattr(model, "result_"):
return
import logging
if not isinstance(model.result_, DivikResult):
logging.info("Skipping DiviK details save. Cause: result is None")
return
logging.info("Saving DiviK partitions.")
merged = make_merged(model.result_).astype(np.int64)
assert merged.shape[0] == model.result_.clustering.labels_.size
xy = kwargs.get("xy", None)
save_merged(fname_fn, merged, xy)
```