Completed
Push — master ( 769c99...57e143 )
by Andrei
01:09
created

bang.process()   A

Complexity

Conditions 1

Size

Total Lines 12

Duplication

Lines 0
Ratio 0 %

Importance

Changes 0
Metric Value
cc 1
dl 0
loc 12
rs 9.4285
c 0
b 0
f 0
1
"""!
2
3
@brief Cluster analysis algorithm: BANG.
4
@details Implementation based on paper @cite inproceedings::bang::1.
5
6
@authors Andrei Novikov ([email protected])
7
@date 2014-2018
8
@copyright GNU Public License
9
10
@cond GNU_PUBLIC_LICENSE
11
    PyClustering is free software: you can redistribute it and/or modify
12
    it under the terms of the GNU General Public License as published by
13
    the Free Software Foundation, either version 3 of the License, or
14
    (at your option) any later version.
15
16
    PyClustering is distributed in the hope that it will be useful,
17
    but WITHOUT ANY WARRANTY; without even the implied warranty of
18
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
19
    GNU General Public License for more details.
20
21
    You should have received a copy of the GNU General Public License
22
    along with this program.  If not, see <http://www.gnu.org/licenses/>.
23
@endcond
24
25
"""
26
27
28
import matplotlib
0 ignored issues
show
Configuration introduced by
The import matplotlib could not be resolved.

This can be caused by one of the following:

1. Missing Dependencies

This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands.

# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3
Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version.

2. Missing __init__.py files

This error could also result from missing __init__.py files in your module folders. Make sure that you place one file in each sub-folder.

Loading history...
29
import matplotlib.gridspec as gridspec;
0 ignored issues
show
Configuration introduced by
The import matplotlib.gridspec could not be resolved.

This can be caused by one of the following:

1. Missing Dependencies

This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands.

# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3
Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version.

2. Missing __init__.py files

This error could also result from missing __init__.py files in your module folders. Make sure that you place one file in each sub-folder.

Loading history...
30
import matplotlib.pyplot as plt
0 ignored issues
show
Configuration introduced by
The import matplotlib.pyplot could not be resolved.

This can be caused by one of the following:

1. Missing Dependencies

This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands.

# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3
Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version.

2. Missing __init__.py files

This error could also result from missing __init__.py files in your module folders. Make sure that you place one file in each sub-folder.

Loading history...
31
import matplotlib.patches as patches
0 ignored issues
show
Configuration introduced by
The import matplotlib.patches could not be resolved.

This can be caused by one of the following:

1. Missing Dependencies

This error could indicate a configuration issue of Pylint. Make sure that your libraries are available by adding the necessary commands.

# .scrutinizer.yml
before_commands:
    - sudo pip install abc # Python2
    - sudo pip3 install abc # Python3
Tip: We are currently not using virtualenv to run pylint, when installing your modules make sure to use the command for the correct version.

2. Missing __init__.py files

This error could also result from missing __init__.py files in your module folders. Make sure that you place one file in each sub-folder.

Loading history...
32
33
import itertools
34
35
from pyclustering.cluster import cluster_visualizer
36
from pyclustering.cluster.encoder import type_encoding
37
38
from pyclustering.utils import data_corners
39
from pyclustering.utils.color import color as color_list
40
41
42
43
class bang_visualizer:
44
    """!
45
    @brief Visualizer of BANG algorithm's results.
46
    @details BANG visualizer provides visualization services that are specific for BANG algorithm.
47
48
    """
49
50
51
    __maximum_density_alpha = 0.6
52
53
54
    @staticmethod
55
    def show_blocks(directory):
56
        """!
57
        @brief Show BANG-blocks (leafs only) in data space.
58
        @details BANG-blocks represents grid that was used for clustering process.
59
60
        @param[in] directory (bang_directory): Directory that was created by BANG algorithm during clustering process.
61
62
        """
63
64
        dimension = len(directory.get_data()[0])
65
66
        amount_canvases = 1
67
        if dimension > 1:
68
            amount_canvases = int(dimension * (dimension - 1) / 2)
69
70
        figure = plt.figure();
71
        grid_spec = gridspec.GridSpec(1, amount_canvases);
72
73
        pairs = list(itertools.combinations(range(dimension), 2))
74
        if len(pairs) == 0: pairs = [(0, 0)]
75
76
        for index in range(amount_canvases):
77
            ax = figure.add_subplot(grid_spec[index]);
78
            bang_visualizer.__draw_blocks(ax, directory.get_leafs(), pairs[index])
79
            bang_visualizer.__draw_two_dimension_data(ax, directory.get_data(), pairs[index])
80
81
        plt.show()
82
83
84
    @staticmethod
85
    def show_dendrogram(dendrogram):
86
        """!
87
        @brief Display dendrogram of BANG-blocks.
88
89
        @param[in] dendrogram (list): List representation of dendrogram of BANG-blocks.
90
91
        @see bang.get_dendrogram()
92
93
        """
94
        plt.figure()
95
        axis = plt.subplot(1, 1, 1)
96
97
        current_position = 0
98
        for index_cluster in range(len(dendrogram)):
99
            densities = [ block.get_density() for block in dendrogram[index_cluster] ]
100
            xrange = range(current_position, current_position + len(densities))
101
102
            axis.bar(xrange, densities, 1.0, linewidth=0.0, color=color_list.get_color(index_cluster))
103
104
            current_position += len(densities)
105
106
        axis.set_ylabel("density")
107
        axis.set_xlabel("block")
108
        axis.xaxis.set_ticklabels([]);
109
110
        plt.xlim([-0.5, current_position - 0.5])
111
        plt.show()
112
113
114
    @staticmethod
115
    def show_clusters(data, clusters, noise=[]):
0 ignored issues
show
Bug Best Practice introduced by
The default value [] might cause unintended side-effects.

Objects as default values are only created once in Python and not on each invocation of the function. If the default object is modified, this modification is carried over to the next invocation of the method.

# Bad:
# If array_param is modified inside the function, the next invocation will
# receive the modified object.
def some_function(array_param=[]):
    # ...

# Better: Create an array on each invocation
def some_function(array_param=None):
    array_param = array_param or []
    # ...
Loading history...
116
        """!
117
        @brief Display K-Means clustering results.
118
119
        @param[in] data (list): Dataset that was used for clustering.
120
        @param[in] clusters (array_like): Clusters that were allocated by the algorithm.
121
        @param[in] noise (array_like): Noise that were allocated by the algorithm.
122
123
        """
124
        visualizer = cluster_visualizer()
125
        visualizer.append_clusters(clusters, data)
126
        visualizer.append_cluster(noise, data, marker='x')
127
        visualizer.show()
128
129
130
    @staticmethod
131
    def __draw_two_dimension_data(ax, data, pair):
132
        """!
133
        @brief Display data in two-dimensional canvas.
134
135
        @param[in] ax (Axis): Canvas where data should be displayed.
136
        @param[in] data (list): Data points that should be displayed.
137
        @param[in] pair (tuple): Pair of dimension indexes.
138
139
        """
140
        ax.set_xlabel("x%d" % pair[0])
141
        ax.set_ylabel("x%d" % pair[1])
142
143
        for point in data:
144
            if len(data[0]) > 1:
145
                ax.plot(point[pair[0]], point[pair[1]], color='red', marker='.')
146
            else:
147
                ax.plot(point[pair[0]], 0, color='red', marker='.')
148
                ax.yaxis.set_ticklabels([]);
149
150
151
    @staticmethod
152
    def __draw_blocks(ax, blocks, pair):
153
        """!
154
        @brief Display BANG-blocks on specified figure.
155
156
        @param[in] ax (Axis): Axis where bang-blocks should be displayed.
157
        @param[in] blocks (list): List of blocks that should be displyed.
158
        @param[in] pair (tuple): Pair of coordinate index that should be displyed.
159
160
        """
161
        ax.grid(False)
162
163
        density_scale = blocks[-1].get_density()
164
        for block in blocks:
165
            bang_visualizer.__draw_block(ax, pair, block, density_scale)
166
167
168
    @staticmethod
169
    def __draw_block(ax, pair, block, density_scale):
170
        """!
171
        @brief Display BANG-block on the specified ax.
172
173
        @param[in] ax (Axis): Axis where block should be displayed.
174
        @param[in] pair (tuple): Pair of coordinate index that should be displayed.
175
        @param[in] block (bang_block): BANG-block that should be displayed.
176
        @param[in] density_scale (double): Max density to display density of the block by appropriate tone.
177
178
        """
179
        max_corner, min_corner = bang_visualizer.__get_rectangle_description(block, pair)
180
181
        belong_cluster = block.get_cluster() is not None
182
183
        density_scale = bang_visualizer.__maximum_density_alpha * block.get_density() / density_scale
184
185
        face_color = matplotlib.colors.to_rgba('blue', alpha=density_scale)
186
        edge_color = matplotlib.colors.to_rgba('black', alpha=1.0)
187
188
        rect = patches.Rectangle(min_corner, max_corner[0] - min_corner[0], max_corner[1] - min_corner[1],
189
                                 fill=belong_cluster,
190
                                 facecolor=face_color,
191
                                 edgecolor=edge_color,
192
                                 linewidth=0.5)
193
        ax.add_patch(rect)
194
195
196
    @staticmethod
197
    def __get_rectangle_description(block, pair):
198
        """!
199
        @brief Create rectangle description for block in specific dimension.
200
201
        @param[in] pair (tuple): Pair of coordinate index that should be displayed.
202
        @param[in] block (bang_block): BANG-block that should be displayed
203
204
        @return (tuple) Pair of corners that describes rectangle.
205
206
        """
207
        max_corner, min_corner = block.get_spatial_block().get_corners()
208
209
        max_corner = [max_corner[pair[0]], max_corner[pair[1]]]
210
        min_corner = [min_corner[pair[0]], min_corner[pair[1]]]
211
212
        if pair == (0, 0):
213
            max_corner[1], min_corner[1] = 1.0, -1.0
214
215
        return max_corner, min_corner
216
217
218
class bang_directory:
219
    """!
220
    @brief BANG directory stores BANG-blocks that represents grid in data space.
221
    @details The directory build BANG-blocks in binary tree manner. Leafs of the tree stored separately to provide
222
              a direct access to the leafs that should be analysed. Leafs cache data-points.
223
224
    """
225
    def __init__(self, data, levels, density_threshold=0.0):
226
        """!
227
        @brief Create BANG directory - basically tree structure with direct access to leafs.
228
229
        @param[in] data (list): Input data that is clustered.
230
        @param[in] levels (uint): Height of the blocks tree.
231
        @param[in] density_threshold (double): The lowest level of density when contained data by bang-block is
232
                    considered as a noise and there is no need to split it till the last level.
233
234
        """
235
        self.__data = data
236
        self.__levels = levels
237
        self.__density_threshold = density_threshold
238
        self.__leafs = []
239
        self.__root = None
240
241
        self.__create_directory()
242
243
244
    def get_data(self):
245
        """!
246
        @brief Return data that is stored in the directory.
247
248
        @return (list) List of points that represents stored data.
249
250
        """
251
        return self.__data
252
253
254
    def get_leafs(self):
255
        """!
256
        @brief Return leafs - the smallest blocks.
257
        @details Some leafs can be bigger than others because splitting is not performed for blocks whose density is
258
                  less than threshold.
259
260
        @return (list) List of blocks that are leafs of BANG directory.
261
262
        """
263
        return self.__leafs
264
265
266
    def __create_directory(self):
267
        """!
268
        @brief Create BANG directory as a tree with separate storage for leafs.
269
270
        """
271
272
        min_corner, max_corner = data_corners(self.__data)
273
        data_block = spatial_block(max_corner, min_corner)
274
275
        cache_require = (self.__levels == 1)
276
        self.__root = bang_block(self.__data, 0, 0, data_block, cache_require)
277
278
        if cache_require:
279
            self.__leafs.append(self.__root)
280
        else:
281
            self.__build_directory_levels()
282
283
284
    def __build_directory_levels(self):
285
        """!
286
        @brief Build levels of direction if amount of level is greater than one.
287
288
        """
289
        previous_level_blocks = [ self.__root ]
290
        for level in range(1, self.__levels):
291
            previous_level_blocks = self.__build_level(previous_level_blocks, level)
292
293
        self.__leafs = sorted(self.__leafs, key=lambda block: block.get_density())
294
295
296
    def __build_level(self, previous_level_blocks, level):
297
        """!
298
        @brief Build new level of directory.
299
300
        @param[in] previous_level_blocks (list): BANG-blocks on the previous level.
301
        @param[in] level (uint): Level number that should be built.
302
303
        @return (list) New block on the specified level.
304
305
        """
306
        current_level_blocks = []
307
308
        split_dimension = level % len(self.__data[0])
309
        cache_require = (level == self.__levels - 1)
310
311
        for block in previous_level_blocks:
312
            self.__split_block(block, split_dimension, cache_require, current_level_blocks)
313
314
        if cache_require:
315
            self.__leafs += current_level_blocks
316
317
        return current_level_blocks
318
319
320
    def __split_block(self, block, split_dimension, cache_require, current_level_blocks):
321
        """!
322
        @brief Split specific block in specified dimension.
323
        @details Split is not performed for block whose density is lower than threshold value, such blocks are putted to
324
                  leafs.
325
326
        @param[in] block (bang_block): BANG-block that should be split.
327
        @param[in] split_dimension (uint): Dimension at which splitting should be performed.
328
        @param[in] cache_require (bool): Defines when points in cache should be stored during density calculation.
329
        @param[in|out] current_level_blocks (list): Block storage at the current level where new blocks should be added.
330
331
        """
332
        if block.get_density() <= self.__density_threshold:
333
            self.__leafs.append(block)
334
335
        else:
336
            left, right = block.split(split_dimension, cache_require)
337
            current_level_blocks.append(left)
338
            current_level_blocks.append(right)
339
340
341
342
class spatial_block:
343
    """!
344
    @brief Geometrical description of BANG block in data space.
345
    @details Provides services related to spatial function and used by bang_block
346
347
    @see bang_block
348
349
    """
350
351
    def __init__(self, max_corner, min_corner):
352
        """!
353
        @brief Creates spatial block in data space.
354
355
        @param[in] max_corner (array_like): Maximum corner coordinates of the block.
356
        @param[in] min_corner (array_like): Minimal corner coordinates of the block.
357
358
        """
359
        self.__max_corner = max_corner
360
        self.__min_corner = min_corner
361
        self.__volume = self.__calculate_volume()
362
363
364
    def __str__(self):
365
        """!
366
        @brief Returns string block description.
367
368
        @return String representation of the block.
369
370
        """
371
        return "(max: %s; min: %s)" % (self.__max_corner, self.__min_corner)
372
373
374
    def __contains__(self, point):
375
        """!
376
        @brief Point is considered as contained if it lies in block (belong to it).
377
378
        @return (bool) True if point is in block, otherwise False.
379
380
        """
381
        for i in range(len(point)):
382
            if point[i] < self.__min_corner[i] or point[i] > self.__max_corner[i]:
383
                return False
384
385
        return True
386
387
388
    def get_corners(self):
389
        """!
390
        @brief Return spatial description of current block.
391
392
        @return (tuple) Pair of maximum and minimum corners (max_corner, min_corner).
393
394
        """
395
        return self.__max_corner, self.__min_corner
396
397
398
    def get_volume(self):
399
        """!
400
        @brief Returns volume of current block.
401
        @details Volume block has uncommon mining here: for 1D is length of a line, for 2D is square of rectangle,
402
                  for 3D is volume of 3D figure, and for ND is volume of ND figure.
403
404
        @return (double) Volume of current block.
405
406
        """
407
        return self.__volume
408
409
410
    def split(self, dimension):
411
        """!
412
        @brief Split current block into two spatial blocks in specified dimension.
413
414
        @param[in] dimension (uint): Dimension where current block should be split.
415
416
        @return (tuple) Pair of new split blocks from current block.
417
418
        """
419
        first_max_corner = self.__max_corner[:]
420
        second_min_corner = self.__min_corner[:]
421
422
        split_border = (self.__max_corner[dimension] + self.__min_corner[dimension]) / 2.0
423
424
        first_max_corner[dimension] = split_border
425
        second_min_corner[dimension] = split_border
426
427
        return spatial_block(first_max_corner, self.__min_corner), spatial_block(self.__max_corner, second_min_corner)
428
429
430
    def is_neighbor(self, block):
431
        """!
432
        @brief Performs calculation to identify whether specified block is neighbor of current block.
433
434
        @param[in] block (spatial_block): Another block that is check whether it is neighbor.
435
436
        @return (bool) True is blocks are neighbors, False otherwise.
437
438
        """
439
        if block is not self:
440
            block_max_corner, _ = block.get_corners()
441
            dimension = len(block_max_corner)
442
            neighborhood_score = self.__calculate_neighborhood(block_max_corner)
443
444
            if neighborhood_score == dimension:
445
                return True
446
447
        return False
448
449
450
    def __calculate_neighborhood(self, block_max_corner):
451
        """!
452
        @brief Calculates neighborhood score that defined whether blocks are neighbors.
453
454
        @param[in] block_max_corner (list): Maximum coordinates of other block.
455
456
        @return (uint) Neighborhood score.
457
458
        """
459
        dimension = len(block_max_corner)
460
461
        length_edges = [self.__max_corner[i] - self.__min_corner[i] for i in range(dimension)]
462
463
        neighborhood_score = 0
464
        for i in range(dimension):
465
            diff = abs(block_max_corner[i] - self.__max_corner[i])
466
467
            if diff <= length_edges[i] + length_edges[i] * 0.0001:
468
                neighborhood_score += 1
469
470
        return neighborhood_score
471
472
473
    def __calculate_volume(self):
474
        """!
475
        @brief Calculates volume of current spatial block.
476
477
        @return (double) Volume of current spatial block.
478
479
        """
480
        volume = self.__max_corner[0] - self.__min_corner[0]
481
        for i in range(1, len(self.__max_corner)):
482
            volume *= self.__max_corner[i] - self.__min_corner[i]
483
484
        return volume
485
486
487
488
class bang_block:
489
    """!
490
    @brief BANG-block that represent spatial region in data space.
491
492
    """
493
    def __init__(self, data, region, level, space_block, cache_points=False):
494
        """!
495
        @brief Create BANG-block.
496
497
        @param[in] data (list): List of points that are processed.
498
        @param[in] region (uint): Region number - unique value on a level.
499
        @param[in] level (uint): Level number where block is created.
500
        @param[in] space_block (spatial_block): Spatial block description in data space.
501
        @param[in] cache_points (bool): if True then points are stored in memory (used for leaf blocks).
502
503
        """
504
        self.__data = data
505
        self.__region_number = region
506
        self.__level = level
507
        self.__spatial_block = space_block
508
        self.__cache_points = cache_points
509
510
        self.__cluster = None
511
        self.__points = None
512
        self.__density = self.__calculate_density()
513
514
515
    def __str__(self):
516
        """!
517
        @brief Returns string representation of BANG-block using region number and level where block is located.
518
519
        """
520
        return "(" + str(self.__region_number) + ", " + str(self.__level) + ")"
521
522
523
    def get_region(self):
524
        """!
525
        @brief Returns region number of BANG-block.
526
        @details Region number is unique on among region numbers on a directory level. Pair of region number and level
527
                  is unique for all directory.
528
529
        @return (uint) Region number.
530
531
        """
532
        return self.__region_number
533
534
535
    def get_density(self):
536
        """!
537
        @brief Returns density of the BANG-block.
538
539
        @return (double) BANG-block density.
540
541
        """
542
        return self.__density
543
544
545
    def get_cluster(self):
546
        """!
547
        @brief Return index of cluster to which the BANG-block belongs to.
548
        @details Index of cluster may have None value if the block was not assigned to any cluster.
549
550
        @return (uint) Index of cluster or None if the block does not belong to any cluster.
551
552
        """
553
        return self.__cluster
554
555
556
    def get_spatial_block(self):
557
        """!
558
        @brief Return spatial block - BANG-block description in data space.
559
560
        @return (spatial_block) Spatial block of the BANG-block.
561
562
        """
563
        return self.__spatial_block
564
565
566
    def get_points(self):
567
        """!
568
        @brief Return points that covers by the BANG-block.
569
570
        @return (list) List of point indexes that are covered by the block.
571
572
        """
573
        if self.__points is None:
574
            self.__cache_covered_data()
575
576
        return self.__points
577
578
579
    def set_cluster(self, index):
580
        """!
581
        @brief Assign cluster to the BANG-block by index.
582
583
        @param[in] index (uint): Index cluster that is assigned to BANG-block.
584
585
        """
586
        self.__cluster = index
587
588
589
    def is_neighbor(self, block):
590
        """!
591
        @brief Performs calculation to check whether specified block is neighbor to the current.
592
593
        @param[in] block (bang_block): Other BANG-block that should be checked for neighborhood.
594
595
        @return (bool) True if blocks are neighbors, False if blocks are not neighbors.
596
597
        """
598
        return self.get_spatial_block().is_neighbor(block.get_spatial_block())
599
600
601
    def split(self, split_dimension, cache_points):
602
        """!
603
        @brief Split BANG-block into two new blocks in specified dimension.
604
605
        @param[in] split_dimension (uint): Dimension where block should be split.
606
        @param[in] cache_points (bool): If True then covered points are cached. Used for leaf blocks.
607
608
        @return (tuple) Pair of BANG-block that were formed from the current.
609
610
        """
611
        left_region_number = self.__region_number
612
        right_region_number = self.__region_number + 2 ** self.__level
613
614
        first_spatial_block, second_spatial_block = self.__spatial_block.split(split_dimension)
615
616
        left = bang_block(self.__data, left_region_number, self.__level + 1, first_spatial_block, cache_points)
617
        right = bang_block(self.__data, right_region_number, self.__level + 1, second_spatial_block, cache_points)
618
619
        return left, right
620
621
622
    def __calculate_density(self):
623
        """!
624
        @brief Calculates BANG-block density.
625
626
        @return (double) BANG-block density.
627
628
        """
629
        return self.__get_amount_points() / self.__spatial_block.get_volume()
630
631
632
    def __get_amount_points(self):
633
        """!
634
        @brief Count covered points by the BANG-block and if cache is enable then covered points are stored.
635
636
        @return (uint) Amount of covered points.
637
638
        """
639
        amount = 0
640
        for index in range(len(self.__data)):
641
            if self.__data[index] in self.__spatial_block:
642
                self.__cache_point(index)
643
                amount += 1
644
645
        return amount
646
647
648
    def __cache_covered_data(self):
649
        """!
650
        @brief Cache covered data.
651
652
        """
653
        self.__cache_points = True
654
        self.__points = []
655
656
        for index_point in range(len(self.__data)):
657
            if self.__data[index_point] in self.__spatial_block:
658
                self.__cache_point(index_point)
659
660
661
    def __cache_point(self, index):
662
        """!
663
        @brief Store index points.
664
665
        @param[in] index (uint): Index point that should be stored.
666
667
        """
668
        if self.__cache_points:
669
            if self.__points is None:
670
                self.__points = []
671
672
            self.__points.append(index)
673
674
675
676
class bang:
677
    """!
678
    @brief Class implements BANG grid based clustering algorithm.
679
    @details BANG clustering algorithms uses a multidimensional grid structure to organize the value space surrounding
680
              the pattern values. The patterns are grouped into blocks and clustered with respect to the blocks by
681
              a topological neighbor search algorithm @cite inproceedings::bang::1.
682
683
    Code example of BANG usage:
684
    @code
685
        from pyclustering.cluster.bang import bang, bang_visualizer
686
        from pyclustering.utils import read_sample
687
        from pyclustering.samples.definitions import FCPS_SAMPLES
688
689
        # Read data three dimensional data.
690
        data = read_sample(FCPS_SAMPLES.SAMPLE_CHAINLINK)
691
692
        # Prepare algorithm's parameters.
693
        levels = 11
694
695
        # Create instance of BANG algorithm.
696
        bang_instance = bang(data, levels)
697
        bang_instance.process()
698
699
        # Obtain clustering results.
700
        clusters = bang_instance.get_clusters()
701
        noise = bang_instance.get_noise()
702
        directory = bang_instance.get_directory()
703
        dendrogram = bang_instance.get_dendrogram()
704
705
        # Visualize BANG clustering results.
706
        bang_visualizer.show_blocks(directory)
707
        bang_visualizer.show_dendrogram(dendrogram)
708
        bang_visualizer.show_clusters(data, clusters, noise)
709
    @endcode
710
711
    There is visualization of BANG-clustering of three-dimensional data 'chainlink'. BANG-blocks that were formed during
712
    processing are shown on following figure. The darkest color means highest density, blocks that does not cover points
713
    are transparent:
714
    @image html bang_blocks_chainlink.png "Fig. 1. BANG-blocks that cover input data."
715
716
    Here is obtained dendrogram that can be used for further analysis to improve clustering results:
717
    @image html bang_dendrogram_chainlink.png "Fig. 2. BANG dendrogram where the X-axis contains BANG-blocks, the Y-axis contains density."
718
719
    BANG clustering result of 'chainlink' data:
720
    @image html bang_clustering_chainlink.png "Fig. 3. BANG clustering result. Data: 'chainlink'."
721
722
    """
723
724
    def __init__(self, data, levels, density_threshold=0.0, ccore=False):
725
        """!
726
        @brief Create BANG clustering algorithm.
727
728
        @param[in] data (list): Input data (list of points) that should be clustered.
729
        @param[in] levels (uint): Amount of levels in tree (how many times block should be split).
730
        @param[in] density_threshold (double): If block density is smaller than this value then contained data by this
731
                    block is considered as a noise.
732
        @param[in] ccore (bool): Reserved positional argument - not used yet.
733
734
        """
735
        self.__data = data
736
        self.__levels = levels
737
        self.__directory = None
738
        self.__clusters = []
739
        self.__noise = []
740
        self.__cluster_blocks = []
741
        self.__dendrogram = []
742
        self.__density_threshold = density_threshold
743
        self.__ccore = ccore
744
745
        self.__validate_arguments()
746
747
748
    def process(self):
749
        """!
750
        @brief Performs clustering process in line with rules of BANG clustering algorithm.
751
752
        @see get_clusters()
753
        @see get_noise()
754
        @see get_directory()
755
        @see get_dendrogram()
756
757
        """
758
        self.__directory = bang_directory(self.__data, self.__levels, self.__density_threshold)
759
        self.__allocate_clusters()
760
761
762
    def get_clusters(self):
763
        """!
764
        @brief Returns allocated clusters.
765
766
        @remark Allocated clusters are returned only after data processing (method process()). Otherwise empty list is returned.
767
768
        @return (list) List of allocated clusters, each cluster contains indexes of objects in list of data.
769
770
        @see process()
771
        @see get_noise()
772
773
        """
774
        return self.__clusters
775
776
777
    def get_noise(self):
778
        """!
779
        @brief Returns allocated noise.
780
781
        @remark Allocated noise is returned only after data processing (method process()). Otherwise empty list is returned.
782
783
        @return (list) List of indexes that are marked as a noise.
784
785
        @see process()
786
        @see get_clusters()
787
788
        """
789
        return self.__noise
790
791
792
    def get_directory(self):
793
        """!
794
        @brief Returns grid directory that describes grid of the processed data.
795
796
        @remark Grid directory is returned only after data processing (method process()). Otherwise None value is returned.
797
798
        @return (bang_directory) BANG directory that describes grid of process data.
799
800
        @see process()
801
802
        """
803
        return self.__directory
804
805
806
    def get_dendrogram(self):
807
        """!
808
        @brief Returns dendrogram of clusters.
809
        @details Dendrogram is created in following way: the density indices of all regions are calculated and sorted
810
                  in decreasing order for each cluster during clustering process.
811
812
        @remark Dendrogram is returned only after data processing (method process()). Otherwise empty list is returned.
813
814
        """
815
        return self.__dendrogram
816
817
818
    def get_cluster_encoding(self):
819
        """!
820
        @brief Returns clustering result representation type that indicate how clusters are encoded.
821
822
        @return (type_encoding) Clustering result representation.
823
824
        @see get_clusters()
825
826
        """
827
828
        return type_encoding.CLUSTER_INDEX_LIST_SEPARATION
829
830
831
    def __validate_arguments(self):
832
        """!
833
        @brief Check input arguments of BANG algorithm and if one of them is not correct then appropriate exception
834
                is thrown.
835
836
        """
837
        if self.__levels <= 0:
838
            raise ValueError("Incorrect amount of levels '%d'. Level value should be greater than 0." % self.__levels)
839
840
        if len(self.__data) == 0:
841
            raise ValueError("Empty input data. Data should contain at least one point.")
842
843
        if self.__density_threshold < 0:
844
            raise ValueError("Incorrect density threshold '%f'. Density threshold should not be negative." % self.__density_threshold)
845
846
847
    def __allocate_clusters(self):
848
        """!
849
        @brief Performs cluster allocation using leafs of tree in BANG directory (the smallest cells).
850
851
        """
852
        leaf_blocks = self.__directory.get_leafs()
853
        unhandled_block_indexes = set([i for i in range(len(leaf_blocks)) if leaf_blocks[i].get_density() > self.__density_threshold])
854
        appropriate_block_indexes = set(unhandled_block_indexes)
0 ignored issues
show
Unused Code introduced by
The variable appropriate_block_indexes seems to be unused.
Loading history...
855
856
        current_block = self.__find_block_center(leaf_blocks, unhandled_block_indexes)
857
        cluster_index = 0
858
859
        while current_block is not None:
860
            if current_block.get_density() <= self.__density_threshold:
861
                break
862
863
            self.__expand_cluster_block(current_block, cluster_index, leaf_blocks, unhandled_block_indexes)
864
865
            current_block = self.__find_block_center(leaf_blocks, unhandled_block_indexes)
866
            cluster_index += 1
867
868
        self.__store_clustering_results(cluster_index, leaf_blocks)
869
870
871
    def __expand_cluster_block(self, block, cluster_index, leaf_blocks, unhandled_block_indexes):
872
        """!
873
        @brief Expand cluster from specific block that is considered as a central block.
874
875
        @param[in] block (bang_block): Block that is considered as a central block for cluster.
876
        @param[in] cluster_index (uint): Index of cluster that is assigned to blocks that forms new cluster.
877
        @param[in] leaf_blocks (list): Leaf BANG-blocks that are considered during cluster formation.
878
        @param[in] unhandled_block_indexes (set): Set of candidates (BANG block indexes) to become a cluster member. The
879
                    parameter helps to reduce traversing among BANG-block providing only restricted set of block that
880
                    should be considered.
881
882
        """
883
884
        block.set_cluster(cluster_index)
885
        self.__update_cluster_dendrogram(cluster_index, [block])
886
887
        neighbors = self.__find_block_neighbors(block, leaf_blocks, unhandled_block_indexes)
888
        self.__update_cluster_dendrogram(cluster_index, neighbors)
889
890
        for neighbor in neighbors:
891
            neighbor.set_cluster(cluster_index)
892
            neighbor_neighbors = self.__find_block_neighbors(neighbor, leaf_blocks, unhandled_block_indexes)
893
            self.__update_cluster_dendrogram(cluster_index, neighbor_neighbors)
894
895
            neighbors += neighbor_neighbors
896
897
898
    def __store_clustering_results(self, amount_clusters, leaf_blocks):
899
        """!
900
        @brief Stores clustering results in a convenient way.
901
902
        @param[in] amount_clusters (uint): Amount of cluster that was allocated during processing.
903
        @param[in] leaf_blocks (list): Leaf BANG-blocks (the smallest cells).
904
905
        """
906
        self.__clusters = [[] for _ in range(amount_clusters)]
907
        for block in leaf_blocks:
908
            index = block.get_cluster()
909
910
            if index is not None:
911
                self.__clusters[index] += block.get_points()
912
            else:
913
                self.__noise += block.get_points()
914
915
        self.__clusters = [ list(set(cluster)) for cluster in self.__clusters ]
916
        self.__noise = list(set(self.__noise))
917
918
919
    def __find_block_center(self, level_blocks, unhandled_block_indexes):
920
        """!
921
        @brief Search block that is cluster center for new cluster.
922
923
        @return (bang_block) Central block for new cluster, if cluster is not found then None value is returned.
924
925
        """
926
        for i in reversed(range(len(level_blocks))):
927
            if level_blocks[i].get_density() <= self.__density_threshold:
928
                return None
929
930
            if level_blocks[i].get_cluster() is None:
931
                unhandled_block_indexes.remove(i)
932
                return level_blocks[i]
933
934
        return None
935
936
937
    def __find_block_neighbors(self, block, level_blocks, unhandled_block_indexes):
938
        """!
939
        @brief Search block neighbors that are parts of new clusters (density is greater than threshold and that are
940
                not cluster members yet), other neighbors are ignored.
941
942
        @param[in] block (bang_block): BANG-block for which neighbors should be found (which can be part of cluster).
943
        @param[in] level_blocks (list): BANG-blocks on specific level.
944
        @param[in] unhandled_block_indexes (set): Blocks that have not been processed yet.
945
946
        @return (list) Block neighbors that can become part of cluster.
947
948
        """
949
        neighbors = []
950
951
        handled_block_indexes = []
952
        for unhandled_index in unhandled_block_indexes:
953
            if block.is_neighbor(level_blocks[unhandled_index]):
954
                handled_block_indexes.append(unhandled_index)
955
                neighbors.append(level_blocks[unhandled_index])
956
957
                # Maximum number of neighbors is eight
958
                if len(neighbors) == 8:
959
                    break
960
961
        for handled_index in handled_block_indexes:
962
            unhandled_block_indexes.remove(handled_index)
963
964
        return neighbors
965
966
967
    def __update_cluster_dendrogram(self, index_cluster, blocks):
968
        """!
969
        @brief Append clustered blocks to dendrogram.
970
971
        @param[in] index_cluster (uint): Cluster index that was assigned to blocks.
972
        @param[in] blocks (list): Blocks that were clustered.
973
974
        """
975
        if len(self.__dendrogram) <= index_cluster:
976
            self.__dendrogram.append([])
977
978
        blocks = sorted(blocks, key=lambda block: block.get_density(), reverse=True)
979
        self.__dendrogram[index_cluster] += blocks
980