def __init__(self, D:np.ndarray, secondary_distance_type:str,
metric:str='distance', classes:np.ndarray=None,
vectors:np.ndarray=None):
"""Initialize a hubness experiment"""
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if secondary_distance_type not in SEC_DIST.keys():
raise ValueError("Requested secondary distance type unknown.")
if classes is not None:
IO._check_distance_matrix_shape_fits_labels(D, classes)
if vectors is None:
self.embedding_dim = None
else: # got vectors
IO._check_distance_matrix_shape_fits_vectors(D, vectors)
self.embedding_dim = vectors.shape[1]
self.original_distance = D
self.secondary_distance_type = secondary_distance_type
self.classes = classes
self.vectors = vectors
self.metric = metric
self.n = D.shape[0]
# Obtained later through functions:
self.secondary_distance = None
self.hubness = dict()
self.anti_hubs = dict()
self.max_hub_k_occurence = dict()
self.knn_accuracy = dict()
self.gk_index = None
def load_dexter():
"""Load the dexter data set.
.. note:: Deprecated in hub-toolbox 2.3
Will be removed in hub-toolbox 3.0.
Please use IO.load_dexter() instead.
"""
return IO.load_dexter()
def __init__(self, D:np.ndarray=None, classes:np.ndarray=None,
vectors:np.ndarray=None, metric:str='distance'):
"""Initialize a quick hubness analysis.
Parameters
----------
D : ndarray, optional (default: None)
The n x n symmetric distance (similarity) matrix.
Default: load example dataset (dexter).
classes : ndarray, optional (default: None)
The 1 x n class labels. Required for k-NN, GK.
vectors : ndarray, optional (default: None)
The m x n vector data. Required for IntrDim estimation.
metric : {'distance', 'similarity'}
Define whether `D` is a distance or similarity matrix.
"""
self.has_class_data, self.has_vector_data = False, False
if D is None:
print('\n'
'NO PARAMETERS GIVEN! Loading & evaluating DEXTER data set.'
'\n'
'DEXTER is a text classification problem in a bag-of-word \n'
'representation. This is a two-class classification problem\n'
'with sparse continuous input variables. \n'
'This dataset is one of five datasets of the NIPS 2003\n'
'feature selection challenge.\n'
'http://archive.ics.uci.edu/ml/datasets/Dexter\n')
self.D, self.classes, self.vectors = IO.load_dexter()
self.has_class_data, self.has_vector_data = True, True
self.metric = 'distance'
else:
# copy data and ensure correct type (not int16 etc.)
self.D = np.copy(D).astype(np.float64)
if classes is None:
self.classes = None
else:
self.classes = np.copy(classes).astype(np.float64)
self.has_class_data = True
if vectors is None:
self.vectors = None
else:
self.vectors = np.copy(vectors).astype(np.float64)
self.has_vector_data = True
self.metric = metric
self.n = len(self.D)
self.experiments = []
def __init__(self, D, k:int=5, isSimilarityMatrix:bool=False):
self.log = Logging.ConsoleLogging()
if isinstance(D, np.memmap):
self.D = D
else:
self.D = IO.copy_D_or_load_memmap(D, writeable=False)
self.k = k
if isSimilarityMatrix:
self.d_self = -np.inf
self.sort_order = -1 # descending, interested in highest similarity
else:
self.d_self = np.inf
self.sort_order = 1 # ascending, interested in smallest distance
np.random.seed()
def __init__(self, D, isSimilarityMatrix=False):
"""
.. note:: Deprecated in hub-toolbox 2.3
Class will be removed in hub-toolbox 3.0.
Please use static functions instead.
"""
print(
"DEPRECATED: Please use the appropriate MutualProximity."
"mutual_proximity_DISTRIBUTIONTYPE() function instead.",
file=sys.stderr,
)
self.D = IO.copy_D_or_load_memmap(D, writeable=True)
self.log = Logging.ConsoleLogging()
if isSimilarityMatrix:
self.self_value = 1
else:
self.self_value = 0
self.isSimilarityMatrix = isSimilarityMatrix
def __init__(self, D, isSimilarityMatrix=False, missing_values=None, tmp='/tmp/'):
"""
.. note:: Deprecated in hub-toolbox 2.3
Class will be removed in hub-toolbox 3.0.
Please use static functions instead.
"""
print("DEPRECATED: Please use the appropriate MutualProximity_parallel."
"mutual_proximity_DISTRIBUTIONTYPE() function instead.",
file=sys.stderr)
self.D = IO.copy_D_or_load_memmap(D, writeable=True)
self.log = Logging.ConsoleLogging()
if isSimilarityMatrix:
self.self_value = 1
else:
self.self_value = 0
self.isSimilarityMatrix = isSimilarityMatrix
self.tmp = tmp
if missing_values is None:
if issparse(D):
self.mv = 0
else:
self.mv = None
else:
self.mv = missing_values
def test_check_dist_vs_vectors(self):
with self.assertRaises(TypeError):
D = np.zeros((5, 5))
vectors = np.zeros((4, 5))
IO._check_distance_matrix_shape_fits_vectors(D, vectors)
def test_check_dist_vs_classes(self):
with self.assertRaises(TypeError):
D = np.empty((5, 5))
classes = np.empty(4)
IO._check_distance_matrix_shape_fits_labels(D, classes)
def test_check_shape(self):
with self.assertRaises(TypeError):
d = np.empty((2, 3))
IO._check_distance_matrix_shape(d)
def score(D:np.ndarray, target:np.ndarray, k=5,
metric:str='distance', test_set_ind:np.ndarray=None, verbose:int=0):
"""Perform `k`-nearest neighbor classification.
Use the ``n x n`` symmetric distance matrix `D` and target class
labels `target` to perform a `k`-NN experiment (leave-one-out
cross-validation or evaluation of test set; see parameter `test_set_ind`).
Ties are broken by the nearest neighbor.
Parameters
----------
D : ndarray
The ``n x n`` symmetric distance (similarity) matrix.
target : ndarray (of dtype=int)
The ``n x 1`` target class labels (ground truth).
k : int or array_like (of dtype=int), optional (default: 5)
Neighborhood size for `k`-NN classification.
For each value in `k`, one `k`-NN experiment is performed.
HINT: Providing more than one value for `k` is a cheap means to perform
multiple `k`-NN experiments at once. Try e.g. ``k=[1, 5, 20]``.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Perform a LOO-CV experiment
- ndarray : Hold out points indexed in this array as test set. Fit
model to remaining data. Evaluate model on test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
Returns
-------
acc : ndarray (shape=(n_k x 1), dtype=float)
Classification accuracy (`n_k`... number of items in parameter `k`)
HINT: Refering to the above example...
... ``acc[0]`` gives the accuracy of the ``k=1`` experiment.
corr : ndarray (shape=(n_k x n), dtype=int)
Raw vectors of correctly classified items
HINT: ... ``corr[1, :]`` gives these items for the ``k=5`` experiment.
cmat : ndarray (shape=(n_k x n_t x n_t), dtype=int)
Confusion matrix (``n_t`` number of unique items in parameter target)
HINT: ... ``cmat[2, :, :]`` gives the confusion matrix of
the ``k=20`` experiment.
"""
# Check input sanity
log = Logging.ConsoleLogging()
IO._check_distance_matrix_shape(D)
IO._check_distance_matrix_shape_fits_labels(D, target)
IO._check_valid_metric_parameter(metric)
if metric == 'distance':
d_self = np.inf
sort_order = 1
if metric == 'similarity':
d_self = -np.inf
sort_order = -1
# Copy, because data is changed
D = D.copy()
target = target.astype(int)
if verbose:
log.message("Start k-NN experiment.")
# Handle LOO-CV vs. test set mode
if test_set_ind is None:
n = D.shape[0]
test_set_ind = range(n) # dummy
train_set_ind = n # dummy
else:
# number of points to be classified
n = test_set_ind.size
# Indices of training examples
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
# Number of k-NN parameters
try:
k_length = k.size
except AttributeError as e:
if isinstance(k, int):
k = np.array([k])
k_length = k.size
elif isinstance(k, list):
k = np.array(k)
k_length = k.size
else:
raise e
acc = np.zeros((k_length, 1))
corr = np.zeros((k_length, D.shape[0]))
cl = np.sort(np.unique(target))
cmat = np.zeros((k_length, len(cl), len(cl)))
classes = target.copy()
for idx, cur_class in enumerate(cl):
# change labels to 0, 1, ..., len(cl)-1
classes[target == cur_class] = idx
cl = range(len(cl))
# Classify each point in test set
for i in test_set_ind:
seed_class = classes[i]
if issparse(D):
row = D.getrow(i).toarray().ravel()
else:
row = D[i, :]
row[i] = d_self
# Sort points in training set according to distance
# Randomize, in case there are several points of same distance
# (this is especially relevant for SNN rescaling)
rp = train_set_ind
rp = np.random.permutation(rp)
d2 = row[rp]
d2idx = np.argsort(d2, axis=0)[::sort_order]
idx = rp[d2idx]
# More than one k is useful for cheap multiple k-NN experiments at once
for j in range(k_length):
nn_class = classes[idx[0:k[j]]]
cs = np.bincount(nn_class.astype(int))
max_cs = np.where(cs == np.max(cs))[0]
# "tie": use nearest neighbor
if len(max_cs) > 1:
if seed_class == nn_class[0]:
acc[j] += 1/n
corr[j, i] = 1
cmat[j, seed_class, nn_class[0]] += 1
# majority vote
else:
if cl[max_cs[0]] == seed_class:
acc[j] += 1/n
corr[j, i] = 1
cmat[j, seed_class, cl[max_cs[0]]] += 1
if verbose:
log.message("Finished k-NN experiment.")
return acc, corr, cmat
def mutual_proximity_gammai(D:np.ndarray, metric:str='distance',
test_set_ind:np.ndarray=None, verbose:int=0,
n_jobs:int=-1, mv=None):
"""Transform a distance matrix with Mutual Proximity (indep. Gamma distr.).
Applies Mutual Proximity (MP) [1]_ on a distance/similarity matrix. Gammai
variant assumes independent Gamma distributed distances (FAST).
The resulting second. distance/similarity matrix should show lower hubness.
Parameters
----------
D : ndarray or csr_matrix
- ndarray: The ``n x n`` symmetric distance or similarity matrix.
- csr_matrix: The ``n x n`` symmetric similarity matrix.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
NOTE: In case of sparse `D`, only 'similarity' is supported.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
n_jobs : int, optional (default: -1)
Number of parallel processes to be used.
NOTE: set ``n_jobs=-1`` to use all CPUs
Returns
-------
D_mp : ndarray
Secondary distance MP gammai matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
log = Logging.ConsoleLogging()
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
n = D.shape[0]
sample_size = 0 # not implemented
if test_set_ind is None:
train_set_ind = slice(0, n)
else:
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
if issparse(D):
return _mutual_proximity_gammai_sparse(D, sample_size, train_set_ind,
verbose, log, mv, n_jobs)
else:
log.warning("MP gammai does not support parallel execution for dense "
"matrices at the moment. Continuing with 1 process.")
from hub_toolbox.MutualProximity import mutual_proximity_gammai
return mutual_proximity_gammai(D, metric, test_set_ind, verbose)
def mutual_proximity_gammai(D: np.ndarray, metric: str = "distance", test_set_ind: np.ndarray = None, verbose: int = 0):
"""Transform a distance matrix with Mutual Proximity (indep. Gamma distr.).
Applies Mutual Proximity (MP) [1]_ on a distance/similarity matrix. Gammai
variant assumes independent Gamma distributed distances (FAST).
The resulting second. distance/similarity matrix should show lower hubness.
Parameters
----------
D : ndarray or csr_matrix
- ndarray: The ``n x n`` symmetric distance or similarity matrix.
- csr_matrix: The ``n x n`` symmetric similarity matrix.
NOTE: In case of sparse `D`, zeros are interpreted as missing values
and ignored during calculations. Thus, results may differ
from using a dense version.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
NOTE: In case of sparse `D`, only 'similarity' is supported.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
Returns
-------
D_mp : ndarray
Secondary distance MP gammai matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
# Initialization
n = D.shape[0]
log = Logging.ConsoleLogging()
# Checking input
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == "similarity":
self_value = 1
else: # metric == 'distance':
self_value = 0
if test_set_ind is None:
train_set_ind = slice(0, n)
else:
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
# Start MP
if verbose:
log.message("Mutual proximity Gammai rescaling started.", flush=True)
D = D.copy()
if issparse(D):
return _mutual_proximity_gammai_sparse(D, test_set_ind, verbose, log)
np.fill_diagonal(D, np.nan)
mu = np.nanmean(D[train_set_ind], 0)
va = np.nanvar(D[train_set_ind], 0, ddof=1)
A = (mu ** 2) / va
B = va / mu
D_mp = np.zeros_like(D)
# MP gammai
for i in range(n):
if verbose and ((i + 1) % 1000 == 0 or i + 1 == n):
log.message("MP_gammai: {} of {}".format(i + 1, n), flush=True)
j_idx = slice(i + 1, n)
if metric == "similarity":
p1 = _local_gamcdf(D[i, j_idx], A[i], B[i])
p2 = _local_gamcdf(D[j_idx, i], A[j_idx], B[j_idx])
D_mp[i, j_idx] = (p1 * p2).ravel()
else: # distance
p1 = 1 - _local_gamcdf(D[i, j_idx], A[i], B[i])
p2 = 1 - _local_gamcdf(D[j_idx, i], A[j_idx], B[j_idx])
D_mp[i, j_idx] = (1 - p1 * p2).ravel()
# Mirroring the matrix
D_mp += D_mp.T
# set correct self dist/sim
np.fill_diagonal(D_mp, self_value)
return D_mp
def mutual_proximity_gauss(D: np.ndarray, metric: str = "distance", test_set_ind: np.ndarray = None, verbose: int = 0):
"""Transform a distance matrix with Mutual Proximity (normal distribution).
Applies Mutual Proximity (MP) [1]_ on a distance/similarity matrix. Gauss
variant assumes dependent normal distributions (VERY SLOW).
The resulting second. distance/similarity matrix should show lower hubness.
Parameters
----------
D : ndarray
- ndarray: The ``n x n`` symmetric distance or similarity matrix.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
Returns
-------
D_mp : ndarray
Secondary distance MP gauss matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
# Initialization
n = D.shape[0]
log = Logging.ConsoleLogging()
# Checking input
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == "similarity":
self_value = 1
else: # metric == 'distance':
self_value = 0
if issparse(D):
log.error("Sparse matrices not supported by MP Gauss.")
raise TypeError("Sparse matrices not supported by MP Gauss.")
if test_set_ind is None:
train_set_ind = slice(0, n)
else:
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
# Start MP
D = D.copy()
np.fill_diagonal(D, self_value)
# np.fill_diagonal(D, np.nan)
mu = np.mean(D[train_set_ind], 0)
sd = np.std(D[train_set_ind], 0, ddof=0)
# ===========================================================================
# mu = np.nanmean(D[train_set_ind], 0)
# sd = np.nanstd(D[train_set_ind], 0, ddof=0)
# ===========================================================================
# Code for the BadMatrixSigma error [derived from matlab]
# ===========================================================================
# eps = np.spacing(1)
# epsmat = np.array([[1e5 * eps, 0], [0, 1e5 * eps]])
# ===========================================================================
D_mp = np.zeros_like(D)
# MP Gauss
for i in range(n):
if verbose and ((i + 1) % 1000 == 0 or i + 1 == n):
log.message("MP_gauss: {} of {}.".format(i + 1, n))
for j in range(i + 1, n):
# ===================================================================
# mask = np.isnan(D[[i, j], :])
# D_mask = np.ma.array(D[[i, j], :], mask=mask)
# c = np.ma.cov(D_mask, ddof=0)
# ===================================================================
c = np.cov(D[[i, j], :], ddof=0)
x = np.array([D[i, j], D[j, i]])
m = np.array([mu[i], mu[j]])
low = np.tile(np.finfo(np.float32).min, 2)
p12 = mvn.mvnun(low, x, m, c)[0] # [0]...p, [1]...inform
if np.isnan(p12):
# ===============================================================
# power = 7
# while np.isnan(p12):
# c += epsmat * (10**power)
# p12 = mvn.mvnun(low, x, m, c)[0]
# power += 1
# log.warning("p12 is NaN: i={}, j={}. Increased cov matrix by "
# "O({}).".format(i, j, epsmat[0, 0]*(10**power)))
# ===============================================================
p12 = 0.0
log.warning("p12 is NaN: i={}, j={}. Set to zero.".format(i, j))
if metric == "similarity":
D_mp[i, j] = p12
else: # distance
p1 = norm.cdf(D[i, j], mu[i], sd[i])
p2 = norm.cdf(D[i, j], mu[j], sd[j])
D_mp[i, j] = p1 + p2 - p12
D_mp += D_mp.T
np.fill_diagonal(D_mp, self_value)
return D_mp
def hubness(D:np.ndarray, k:int=5, metric='distance',
verbose:int=0, n_jobs:int=-1):
"""Compute hubness of a distance matrix.
Hubness [1]_ is the skewness of the `k`-occurrence histogram (reverse
nearest neighbor count, i.e. how often does a point occur in the
`k`-nearest neighbor lists of other points).
Parameters
----------
D : ndarray
The ``n x n`` symmetric distance (similarity) matrix.
k : int, optional (default: 5)
Neighborhood size for `k`-occurence.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix
verbose : int, optional (default: 0)
Increasing level of output (progress report).
n_jobs : int, optional (default: -1)
Number of parallel processes spawned for hubness calculation.
Default value (-1): number of available CPUs.
Returns
-------
S_k : float
Hubness (skewness of `k`-occurence distribution)
D_k : ndarray
`k`-nearest neighbor lists
N_k : ndarray
`k`-occurence list
References
----------
.. [1] Radovanović, M., Nanopoulos, A., & Ivanović, M. (2010).
Hubs in Space : Popular Nearest Neighbors in High-Dimensional Data.
Journal of Machine Learning Research, 11, 2487–2531. Retrieved from
http://jmlr.csail.mit.edu/papers/volume11/radovanovic10a/
radovanovic10a.pdf
"""
log = Logging.ConsoleLogging()
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == 'distance':
d_self = np.inf
sort_order = 1
if metric == 'similarity':
d_self = -np.inf
sort_order = -1
if verbose:
log.message("Hubness calculation (skewness of {}-occurence)".format(k))
# Initialization
n = D.shape[0]
D = D.copy()
D_k = np.zeros((k, D.shape[1]), dtype=np.float32 )
if issparse(D):
pass # correct self-distance must be ensured upstream for sparse
else:
# Set self dist to inf
np.fill_diagonal(D, d_self)
# make non-finite (NaN, Inf) appear at the end of the sorted list
D[~np.isfinite(D)] = d_self
# Parallelization
if n_jobs == -1: # take all cpus
NUMBER_OF_PROCESSES = mp.cpu_count() # @UndefinedVariable
else:
NUMBER_OF_PROCESSES = n_jobs
tasks = []
batches = []
batch_size = n // NUMBER_OF_PROCESSES
for i in range(NUMBER_OF_PROCESSES-1):
batches.append( np.arange(i*batch_size, (i+1)*batch_size) )
batches.append( np.arange((NUMBER_OF_PROCESSES-1)*batch_size, n) )
for idx, batch in enumerate(batches):
submatrix = D[batch[0]:batch[-1]+1]
tasks.append((_partial_hubness,
(k, d_self, log, sort_order,
batch, submatrix, idx, n, verbose)))
task_queue = mp.Queue() # @UndefinedVariable
done_queue = mp.Queue() # @UndefinedVariable
for task in tasks:
task_queue.put(task)
for i in range(NUMBER_OF_PROCESSES): # @UnusedVariable
mp.Process(target=_worker, args=(task_queue, done_queue)).start() # @UndefinedVariable
for i in range(len(tasks)): # @UnusedVariable
rows, Dk_part = done_queue.get()
D_k[:, rows[0]:rows[-1]+1] = Dk_part
for i in range(NUMBER_OF_PROCESSES): # @UnusedVariable
task_queue.put('STOP')
# k-occurence
N_k = np.bincount(D_k.astype(int).ravel())
# Hubness
S_k = stats.skew(N_k)
if verbose:
log.message("Hubness calculation done.", flush=True)
# return hubness, k-nearest neighbors, N occurence
return S_k, D_k, N_k
def local_scaling(D:np.ndarray, k:int=7, metric:str='distance',
test_set_ind:np.ndarray=None):
"""Transform a distance matrix with Local Scaling.
Transforms the given distance matrix into new one using local scaling [1]_
with the given `k`-th nearest neighbor. There are two types of local
scaling methods implemented. The original one and NICDM, both reduce
hubness in distance spaces, similarly to Mutual Proximity.
Parameters
----------
D : ndarray or csr_matrix
The ``n x n`` symmetric distance (similarity) matrix.
k : int, optional (default: 7)
Neighborhood radius for local scaling.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
NOTE: self similarities in sparse `D_ls` are set to ``np.inf``
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
Returns
-------
D_ls : ndarray
Secondary distance LocalScaling matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
log = Logging.ConsoleLogging()
# Checking input
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == 'similarity':
sort_order = -1
exclude = -np.inf
self_tmp_value = np.inf
self_value = 1.
log.warning("Similarity matrix support for LS is experimental.")
else: # metric == 'distance':
sort_order = 1
exclude = np.inf
self_value = 0
self_tmp_value = self_value
if issparse(D):
log.error("Sparse distance matrices are not supported.")
raise NotImplementedError(
"Sparse distance matrices are not supported.")
D = np.copy(D)
n = D.shape[0]
if test_set_ind is None:
train_set_ind = slice(0, n) #take all
else:
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
r = np.zeros(n)
for i in range(n):
if issparse(D):
di = D[i, train_set_ind].toarray()
else:
di = D[i, train_set_ind]
di[i] = exclude
nn = np.argsort(di)[::sort_order]
r[i] = di[nn[k-1]] #largest similarities or smallest distances
if issparse(D):
D_ls = lil_matrix(D.shape)
else:
D_ls = np.zeros_like(D)
for i in range(n):
# vectorized inner loop: calc only triu part
tmp = np.empty(n-i)
tmp[0] = self_tmp_value
if metric == 'similarity':
tmp[1:] = np.exp(-1 * D[i, i+1:]**2 / (r[i] * r[i+1:]))
else:
tmp[1:] = 1 - np.exp(-1 * D[i, i+1:]**2 / (r[i] * r[i+1:]))
D_ls[i, i:] = tmp
# copy triu to tril -> symmetric matrix (diag=zeros)
# NOTE: does not affect self values, since inf+inf=inf and 0+0=0
D_ls += D_ls.T
if issparse(D):
return D_ls.tocsr()
else:
np.fill_diagonal(D_ls, self_value)
return D_ls
def nicdm(D:np.ndarray, k:int=7, metric:str='distance',
test_set_ind:np.ndarray=None):
"""Transform a distance matrix with local scaling variant NICDM.
Transforms the given distance matrix into new one using NICDM [1]_
with the given neighborhood radius `k` (average). There are two types of
local scaling methods implemented. The original one and the non-iterative
contextual dissimilarity measure, both reduce hubness in distance spaces,
similarly to Mutual Proximity.
Parameters
----------
D : ndarray
The ``n x n`` symmetric distance (similarity) matrix.
k : int, optional (default: 7)
Neighborhood radius for local scaling.
metric : {'distance'}, optional (default: 'distance')
Currently, only distance matrices are supported.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
Returns
-------
D_nicdm : ndarray
Secondary distance NICDM matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
#log = Logging.ConsoleLogging()
# Checking input
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == 'similarity':
raise NotImplementedError("NICDM does not support similarity matrices "
"at the moment.")
D = np.copy(D)
if metric == 'distance':
sort_order = 1
exclude = np.inf
else: #metric == 'similarity':
sort_order = -1
exclude = -np.inf
n = D.shape[0]
if test_set_ind is None:
train_set_ind = slice(0, n)
else:
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
knn = np.zeros((n, k))
r = np.zeros(n)
np.fill_diagonal(D, np.inf)
for i in range(n):
di = D[i, :].copy()
di[i] = exclude
di = di[train_set_ind]
nn = np.argsort(di)[::sort_order]
knn[i, :] = di[nn[0:k]] # largest sim. or smallest dist.
r[i] = np.mean(knn[i])
r_geom = _local_geomean(knn.ravel())
D_nicdm = np.zeros_like(D)
for i in range(n):
# vectorized inner loop for 100x speed-up (using broadcasting)
D_nicdm[i, i+1:] = (r_geom * D[i, i+1:]) / np.sqrt(r[i] * r[i+1:])
D_nicdm += D_nicdm.T
return D_nicdm
def hubness(D:np.ndarray, k:int=5, metric='distance', verbose:int=0):
"""Compute hubness of a distance matrix.
Hubness [1]_ is the skewness of the `k`-occurrence histogram (reverse
nearest neighbor count, i.e. how often does a point occur in the
`k`-nearest neighbor lists of other points).
Parameters
----------
D : ndarray
The ``n x n`` symmetric distance (similarity) matrix.
k : int, optional (default: 5)
Neighborhood size for `k`-occurence.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix
verbose : int, optional (default: 0)
Increasing level of output (progress report).
Returns
-------
S_k : float
Hubness (skewness of `k`-occurence distribution)
D_k : ndarray
`k`-nearest neighbor lists
N_k : ndarray
`k`-occurence list
References
----------
.. [1] Radovanović, M., Nanopoulos, A., & Ivanović, M. (2010).
Hubs in Space : Popular Nearest Neighbors in High-Dimensional Data.
Journal of Machine Learning Research, 11, 2487–2531. Retrieved from
http://jmlr.csail.mit.edu/papers/volume11/radovanovic10a/
radovanovic10a.pdf
"""
log = Logging.ConsoleLogging()
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == 'distance':
d_self = np.inf
sort_order = 1
if metric == 'similarity':
d_self = -np.inf
sort_order = -1
if verbose:
log.message("Hubness calculation (skewness of {}-occurence)".format(k))
D = D.copy()
D_k = np.zeros((k, D.shape[1]), dtype=np.float32)
n = D.shape[0]
if issparse(D):
pass # correct self-distance must be ensured upstream for sparse
else:
# Set self dist to inf
np.fill_diagonal(D, d_self)
# make non-finite (NaN, Inf) appear at the end of the sorted list
D[~np.isfinite(D)] = d_self
for i in range(n):
if verbose and ((i+1)%10000==0 or i+1==n):
log.message("NN: {} of {}.".format(i+1, n), flush=True)
if issparse(D):
d = D[i, :].toarray().ravel() # dense copy of one row
else: # normal ndarray
d = D[i, :]
d[i] = d_self
d[~np.isfinite(d)] = d_self
# Randomize equal values in the distance matrix rows to avoid the
# problem case if all numbers to sort are the same, which would yield
# high hubness, even if there is none.
rp = np.random.permutation(n)
d2 = d[rp]
d2idx = np.argsort(d2, axis=0)[::sort_order]
D_k[:, i] = rp[d2idx[0:k]]
# N-occurence
N_k = np.bincount(D_k.astype(int).ravel(), minlength=n)
# Hubness
S_k = stats.skew(N_k)
# return k-hubness, k-nearest neighbors, k-occurence
if verbose:
log.message("Hubness calculation done.", flush=True)
return S_k, D_k, N_k
def test_check_valid_metric(self):
with self.assertRaises(ValueError):
metric = 'dissimilarity'
IO._check_valid_metric_parameter(metric)
def mutual_proximity_empiric(D:np.ndarray, metric:str='distance',
test_set_ind:np.ndarray=None, verbose:int=0,
n_jobs:int=-1):
"""Transform a distance matrix with Mutual Proximity (empiric distribution).
Applies Mutual Proximity (MP) [1]_ on a distance/similarity matrix using
the empiric data distribution (EXACT, rather SLOW). The resulting
secondary distance/similarity matrix should show lower hubness.
Parameters
----------
D : ndarray or csr_matrix
- ndarray: The ``n x n`` symmetric distance or similarity matrix.
- csr_matrix: The ``n x n`` symmetric similarity matrix.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
NOTE: In case of sparse `D`, only 'similarity' is supported.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
n_jobs : int, optional (default: -1)
Number of parallel processes to be used.
NOTE: set ``n_jobs=-1`` to use all CPUs
Returns
-------
D_mp : ndarray
Secondary distance MP empiric matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
log = Logging.ConsoleLogging()
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
# DO NOT DELETE this comment, will be used upon parallel MP emp dist impl
#===========================================================================
# # Initialization
# n = D.shape[0]
#
# # Check input
# if D.shape[0] != D.shape[1]:
# raise TypeError("Distance/similarity matrix is not quadratic.")
# if metric == 'similarity':
# self_value = 1
# elif metric == 'distance':
# self_value = 0
# if issparse(D):
# raise ValueError("MP sparse only supports similarity matrices.")
# else:
# raise ValueError("Parameter 'metric' must be 'distance' "
# "or 'similarity'.")
# if test_set_ind is None:
# pass # TODO implement
# #train_set_ind = slice(0, n)
# elif not np.all(~test_set_ind):
# raise NotImplementedError("MP empiric does not yet support train/"
# "test splits.")
# #train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
#===========================================================================
if issparse(D):
return _mutual_proximity_empiric_sparse(D, test_set_ind, verbose, log, n_jobs)
else:
log.warning("MP empiric does not support parallel execution for dense "
"matrices at the moment. Continuing with 1 process.")
from hub_toolbox.MutualProximity import mutual_proximity_empiric
return mutual_proximity_empiric(D, metric, test_set_ind, verbose)
def shared_nearest_neighbors(D:np.ndarray, k:int=10, metric='distance'):
"""Transform distance matrix using shared nearest neighbors [1]_.
SNN similarity is based on computing the overlap between the `k` nearest
neighbors of two objects. SNN approaches try to symmetrize nearest neighbor
relations using only rank and not distance information [2]_.
Parameters
----------
D : np.ndarray
The ``n x n`` symmetric distance (similarity) matrix.
k : int, optional (default: 10)
Neighborhood radius: The `k` nearest neighbors are used to calculate SNN.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether the matrix `D` is a distance or similarity matrix
Returns
-------
D_snn : ndarray
Secondary distance SNN matrix
References
----------
.. [1] R. Jarvis and E. A. Patrick, “Clustering using a similarity measure
based on shared near neighbors,” IEEE Transactions on Computers,
vol. 22, pp. 1025–1034, 1973.
.. [2] Flexer, A., & Schnitzer, D. (2013). Can Shared Nearest Neighbors
Reduce Hubness in High-Dimensional Spaces? 2013 IEEE 13th
International Conference on Data Mining Workshops, 460–467.
http://doi.org/10.1109/ICDMW.2013.101
"""
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == 'distance':
self_value = 0.
sort_order = 1
exclude = np.inf
if metric == 'similarity':
self_value = 1.
sort_order = -1
exclude = -np.inf
distance = D.copy()
np.fill_diagonal(distance, exclude)
n = np.shape(distance)[0]
knn = np.zeros_like(distance, bool)
# find nearest neighbors for each point
for i in range(n):
di = distance[i, :]
nn = np.argsort(di)[::sort_order]
knn[i, nn[0:k]] = True
D_snn = np.zeros_like(distance)
for i in range(n):
knn_i = knn[i, :]
j_idx = slice(i+1, n)
# using broadcasting
Dij = np.sum(np.logical_and(knn_i, knn[j_idx, :]), 1)
if metric == 'distance':
D_snn[i, j_idx] = 1. - Dij / k
else: # metric == 'similarity':
D_snn[i, j_idx] = Dij / k
D_snn += D_snn.T
np.fill_diagonal(D_snn, self_value)
return D_snn
def mutual_proximity_empiric(
D: np.ndarray, metric: str = "distance", test_set_ind: np.ndarray = None, verbose: int = 0
):
"""Transform a distance matrix with Mutual Proximity (empiric distribution).
Applies Mutual Proximity (MP) [1]_ on a distance/similarity matrix using
the empiric data distribution (EXACT, rather SLOW). The resulting
secondary distance/similarity matrix should show lower hubness.
Parameters
----------
D : ndarray or csr_matrix
- ndarray: The ``n x n`` symmetric distance or similarity matrix.
- csr_matrix: The ``n x n`` symmetric similarity matrix.
NOTE: In case of sparse ``D`, zeros are interpreted as missing values
and ignored during calculations. Thus, results may differ
from using a dense version.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
NOTE: In case of sparse `D`, only 'similarity' is supported.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
Returns
-------
D_mp : ndarray
Secondary distance MP empiric matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
# Initialization
n = D.shape[0]
log = Logging.ConsoleLogging()
# Check input
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == "similarity":
self_value = 1
exclude_value = np.inf
else: # metric == 'distance':
self_value = 0
exclude_value = -np.inf
if issparse(D):
raise ValueError("MP sparse only supports similarity matrices.")
if test_set_ind is None:
pass # TODO implement
# train_set_ind = slice(0, n)
elif not np.all(~test_set_ind):
raise NotImplementedError("MP empiric does not yet support train/" "test splits.")
# train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
# Start MP
D = D.copy()
if issparse(D):
return _mutual_proximity_empiric_sparse(D, test_set_ind, verbose, log)
# ensure correct self distances (NOT done for sparse matrices!)
np.fill_diagonal(D, exclude_value)
D_mp = np.zeros_like(D)
# Calculate MP empiric
for i in range(n - 1):
if verbose and ((i + 1) % 1000 == 0 or i == n - 2):
log.message("MP_empiric: {} of {}.".format(i + 1, n - 1), flush=True)
# Calculate only triu part of matrix
j_idx = i + 1
dI = D[i, :][np.newaxis, :]
dJ = D[j_idx:n, :]
d = D[j_idx:n, i][:, np.newaxis]
if metric == "similarity":
D_mp[i, j_idx:] = np.sum((dI <= d) & (dJ <= d), 1) / (n - 1)
else: # metric == 'distance':
D_mp[i, j_idx:] = 1 - (np.sum((dI > d) & (dJ > d), 1) / (n - 1))
# Mirror, so that matrix is symmetric
D_mp += D_mp.T
np.fill_diagonal(D_mp, self_value)
return D_mp
def shared_nearest_neighbors(D: np.ndarray, k: int = 10, metric='similarity'):
"""Transform distance matrix using shared nearest neighbors [1]_.
SNN similarity is based on computing the overlap between the `k` nearest
neighbors of two objects. SNN approaches try to symmetrize nearest neighbor
relations using only rank and not distance information [2]_.
Parameters
----------
D : np.ndarray
The ``n x n`` symmetric distance (similarity) matrix.
k : int, optional (default: 10)
Neighborhood radius: The `k` nearest neighbors are used to calculate SNN.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether the matrix `D` is a distance or similarity matrix
Returns
-------
D_snn : ndarray
Secondary distance SNN matrix
References
----------
.. [1] R. Jarvis and E. A. Patrick, “Clustering using a similarity measure
based on shared near neighbors,” IEEE Transactions on Computers,
vol. 22, pp. 1025–1034, 1973.
.. [2] Flexer, A., & Schnitzer, D. (2013). Can Shared Nearest Neighbors
Reduce Hubness in High-Dimensional Spaces? 2013 IEEE 13th
International Conference on Data Mining Workshops, 460–467.
http://doi.org/10.1109/ICDMW.2013.101
"""
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
if metric == 'distance':
self_value = 0.
sort_order = 1
exclude = np.inf
if metric == 'similarity':
self_value = 1.
sort_order = -1
exclude = -np.inf
distance = D.copy()
np.fill_diagonal(distance, exclude)
n = np.shape(distance)[0]
knn = np.zeros_like(distance, bool)
# find nearest neighbors for each point
for i in range(n):
di = distance[i, :]
nn = np.argsort(di)[::sort_order]
knn[i, nn[0:k]] = True
D_snn = np.zeros_like(distance)
for i in range(n):
knn_i = knn[i, :]
j_idx = slice(i + 1, n)
# using broadcasting
Dij = np.sum(np.logical_and(knn_i, knn[j_idx, :]), 1)
if metric == 'distance':
D_snn[i, j_idx] = 1. - Dij / k
else: # metric == 'similarity':
D_snn[i, j_idx] = Dij / k
D_snn += D_snn.T
np.fill_diagonal(D_snn, self_value)
return D_snn
def mutual_proximity_gaussi(D:np.ndarray, metric:str='distance',
sample_size:int=0, test_set_ind:np.ndarray=None,
verbose:int=0, n_jobs:int=-1, mv=None):
"""Transform a distance matrix with Mutual Proximity (indep. normal distr.).
Applies Mutual Proximity (MP) [1]_ on a distance/similarity matrix. Gaussi
variant assumes independent normal distributions (FAST).
The resulting second. distance/similarity matrix should show lower hubness.
Parameters
----------
D : ndarray or csr_matrix
- ndarray: The ``n x n`` symmetric distance or similarity matrix.
- csr_matrix: The ``n x n`` symmetric similarity matrix.
metric : {'distance', 'similarity'}, optional (default: 'distance')
Define, whether matrix `D` is a distance or similarity matrix.
NOTE: In case of sparse `D`, only 'similarity' is supported.
sample_size : int, optional (default: 0)
Define sample size from which Gauss parameters are estimated.
Use all data when set to ``0``.
test_sed_ind : ndarray, optional (default: None)
Define data points to be hold out as part of a test set. Can be:
- None : Rescale all distances
- ndarray : Hold out points indexed in this array as test set.
verbose : int, optional (default: 0)
Increasing level of output (progress report).
n_jobs : int, optional (default: -1)
Number of parallel processes to be used.
NOTE: set ``n_jobs=-1`` to use all CPUs
Returns
-------
D_mp : ndarray
Secondary distance MP gaussi matrix.
References
----------
.. [1] Schnitzer, D., Flexer, A., Schedl, M., & Widmer, G. (2012).
Local and global scaling reduce hubs in space. The Journal of Machine
Learning Research, 13(1), 2871–2902.
"""
# Initialization
n = D.shape[0] # @UnusedVariable
log = Logging.ConsoleLogging()
IO._check_distance_matrix_shape(D)
IO._check_valid_metric_parameter(metric)
# DO NOT DELETE comment
#===========================================================================
# # Checking input
# if D.shape[0] != D.shape[1]:
# raise TypeError("Distance/similarity matrix is not quadratic.")
# if metric == 'similarity':
# self_value = 1
# elif metric == 'distance':
# self_value = 0
# else:
# raise ValueError("Parameter metric must be 'distance' or 'similarity'.")
#===========================================================================
if test_set_ind is None:
train_set_ind = slice(0, n)
else:
train_set_ind = np.setdiff1d(np.arange(n), test_set_ind)
#===========================================================================
# # Start MP Gaussi
# if verbose:
# log.message('Mutual Proximity Gaussi rescaling started.', flush=True)
# D = D.copy()
#===========================================================================
if issparse(D):
return _mutual_proximity_gaussi_sparse(D, sample_size, train_set_ind,
verbose, log, mv, n_jobs)
else:
log.warning("MP gaussi does not support parallel execution for dense "
"matrices at the moment. Continuing with 1 process.")
from hub_toolbox.MutualProximity import mutual_proximity_gaussi
return mutual_proximity_gaussi(D, metric, sample_size, test_set_ind, verbose)