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codebook.py
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codebook.py
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import numpy as np
from sklearn.decomposition import RandomizedPCA, PCA
from decorators import timeit
class InvalidNodeIndexError(Exception):
pass
class InvalidMapsizeError(Exception):
pass
class Codebook(object):
def __init__(self, mapsize, lattice='rect'):
self.lattice = lattice
if 2 == len(mapsize):
_size = [1, np.max(mapsize)] if 1 == np.min(mapsize) else mapsize
elif 1 == len(mapsize):
_size = [1, mapsize[0]]
print 'input was considered as the numbers of nodes'
print 'map size is [{dlen},{dlen}]'.format(dlen=int(mapsize[0]/2))
else:
raise InvalidMapsizeError("Mapsize is expected to be a 2 element list or a single int")
self.mapsize = _size
self.nnodes = mapsize[0]*mapsize[1]
self.matrix = np.asarray(self.mapsize)
self.initialized = False
@timeit()
def random_initialization(self, data):
"""
:param data: data to use for the initialization
:returns: initialized matrix with same dimension as input data
"""
mn = np.tile(np.min(data, axis=0), (self.nnodes, 1))
mx = np.tile(np.max(data, axis=0), (self.nnodes, 1))
self.matrix = mn + (mx-mn)*(np.random.rand(self.nnodes, data.shape[1]))
self.initialized = True
@timeit()
def pca_linear_initialization(self, data):
"""
We initialize the map, just by using the first two first eigen vals and eigenvectors
Further, we create a linear combination of them in the new map by giving values from -1 to 1 in each
X = UsigmaWT
XTX = Wsigma^2WT
T = XW = Usigma
// Transformed by W EigenVector, can be calculated by multiplication PC matrix by eigenval too
// Further, we can get lower ranks by using just few of the eigen vevtors
T(2) = U(2)sigma(2) = XW(2) ---> 2 is the number of selected eigenvectors
(*) Note that 'X' is the covariance matrix of original data
:param data: data to use for the initialization
:returns: initialized matrix with same dimension as input data
"""
cols = self.mapsize[1]
coord = None
pca_components = None
if np.min(self.mapsize) > 1:
coord = np.zeros((self.nnodes, 2))
pca_components = 2
for i in range(0, self.nnodes):
coord[i, 0] = int(i / cols) # x
coord[i, 1] = int(i % cols) # y
elif np.min(self.mapsize) == 1:
coord = np.zeros((self.nnodes, 1))
pca_components = 1
for i in range(0, self.nnodes):
coord[i, 0] = int(i % cols) # y
mx = np.max(coord, axis=0)
mn = np.min(coord, axis=0)
coord = (coord - mn)/(mx-mn)
coord = (coord - .5)*2
me = np.mean(data, 0)
data = (data - me)
tmp_matrix = np.tile(me, (self.nnodes, 1))
pca = RandomizedPCA(n_components=pca_components) # Randomized PCA is scalable
pca.fit(data)
eigvec = pca.components_
eigval = pca.explained_variance_
norms = np.sqrt(np.einsum('ij,ij->i', eigvec, eigvec))
eigvec = ((eigvec.T/norms)*eigval).T
for j in range(self.nnodes):
for i in range(eigvec.shape[0]):
tmp_matrix[j, :] = tmp_matrix[j, :] + coord[j, i]*eigvec[i, :]
self.matrix = np.around(tmp_matrix, decimals=6)
self.initialized = True
def grid_dist(self, node_ind):
"""
Calculates grid distance based on the lattice type.
:param node_ind: number between 0 and number of nodes-1. Depending on the map size, starting from top left
:returns: matrix representing the distance matrix
"""
if self.lattice == 'rect':
return self._rect_dist(node_ind)
elif self.lattice == 'hexa':
return self._hexa_dist(node_ind)
def _hexa_dist(self, node_ind):
raise NotImplementedError()
def _rect_dist(self, node_ind):
"""
Calculates the distance of the specified node to the other nodes in the matrix, generating a distance matrix
Ej. The distance matrix for the node_ind=5, that corresponds to the_coord (1,1)
array([[2, 1, 2, 5],
[1, 0, 1, 4],
[2, 1, 2, 5],
[5, 4, 5, 8]])
:param node_ind: number between 0 and number of nodes-1. Depending on the map size, starting from top left
:returns: matrix representing the distance matrix
"""
rows = self.mapsize[0]
cols = self.mapsize[1]
dist = None
# bmu should be an integer between 0 to no_nodes
if 0 <= node_ind <= (rows*cols):
node_col = int(node_ind % cols)
node_row = int(node_ind / cols)
else:
raise InvalidNodeIndexError("Node index '%s' is invalid" % node_ind)
if rows > 0 and cols > 0:
r = np.arange(0, rows, 1)[:, np.newaxis]
c = np.arange(0, cols, 1)
dist2 = (r-node_row)**2 + (c-node_col)**2
dist = dist2.ravel()
else:
raise InvalidMapsizeError("One or both of the map dimensions are invalid. Cols '%s', Rows '%s'".format(
cols=cols,
rows=rows))
return dist