def smacof_mds(C, dim, max_iter=3000, eps=1e-9):
"""
Returns an interpolated point cloud following the dissimilarity matrix C
using SMACOF multidimensional scaling (MDS) in specific dimensionned
target space
Parameters
----------
C : ndarray, shape (ns, ns)
dissimilarity matrix
dim : int
dimension of the targeted space
max_iter : int
Maximum number of iterations of the SMACOF algorithm for a single run
eps : float
relative tolerance w.r.t stress to declare converge
Returns
-------
npos : ndarray, shape (R, dim)
Embedded coordinates of the interpolated point cloud (defined with
one isometry)
"""
rng = np.random.RandomState(seed=3)
mds = manifold.MDS(
dim,
max_iter=max_iter,
eps=1e-9,
dissimilarity='precomputed',
n_init=1)
pos = mds.fit(C).embedding_
nmds = manifold.MDS(
2,
max_iter=max_iter,
eps=1e-9,
dissimilarity="precomputed",
random_state=rng,
n_init=1)
npos = nmds.fit_transform(C, init=pos)
return npos
##############################################################################
# Data preparation
# ----------------
#
# The four distributions are constructed from 4 simple images
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