def __init__(self,
components,
alpha_0=None,
a_0=None,
b_0=None,
weights=None,
weights_obj=None):
assert len(components) > 0
assert (alpha_0 is not None) ^ (a_0 is not None and b_0 is not None) \
^ (weights_obj is not None)
self.components = components
if alpha_0 is not None:
self.weights = Categorical(alpha_0=alpha_0,
K=len(components),
weights=weights)
elif weights_obj is not None:
self.weights = weights_obj
else:
self.weights = CategoricalAndConcentration(a_0=a_0,
b_0=b_0,
K=len(components),
weights=weights)
self.labels_list = []
def __init__(self, components, alpha_0=None, a_0=None, b_0=None, weights=None, weights_obj=None):
assert len(components) > 0
assert (alpha_0 is not None) ^ (a_0 is not None and b_0 is not None) ^ (weights_obj is not None)
self.components = components
if alpha_0 is not None:
self.weights = Categorical(alpha_0=alpha_0, K=len(components), weights=weights)
elif weights_obj is not None:
self.weights = weights_obj
else:
self.weights = CategoricalAndConcentration(a_0=a_0, b_0=b_0, K=len(components), weights=weights)
self.labels_list = []
class Mixture(ModelGibbsSampling, ModelMeanField, ModelEM, ModelParallelTempering):
'''
This class is for mixtures of other distributions.
'''
_labels_class = Labels
def __init__(self,components,alpha_0=None,a_0=None,b_0=None,weights=None,weights_obj=None):
assert len(components) > 0
assert (alpha_0 is not None) ^ (a_0 is not None and b_0 is not None) \
^ (weights_obj is not None)
self.components = components
if alpha_0 is not None:
self.weights = Categorical(alpha_0=alpha_0,K=len(components),weights=weights)
elif weights_obj is not None:
self.weights = weights_obj
else:
self.weights = CategoricalAndConcentration(
a_0=a_0,b_0=b_0,K=len(components),weights=weights)
self.labels_list = []
def add_data(self,data,**kwargs):
self.labels_list.append(self._labels_class(data=np.asarray(data),model=self,**kwargs))
return self.labels_list[-1]
@property
def N(self):
return len(self.components)
def generate(self,N,keep=True):
templabels = self._labels_class(model=self,N=N)
out = np.empty(self.components[0].rvs(N).shape)
counts = np.bincount(templabels.z,minlength=self.N)
for idx,(c,count) in enumerate(zip(self.components,counts)):
out[templabels.z == idx,...] = c.rvs(count)
perm = np.random.permutation(N)
out = out[perm]
templabels.z = templabels.z[perm]
if keep:
templabels.data = out
self.labels_list.append(templabels)
return out, templabels.z
def _clear_caches(self):
for l in self.labels_list:
l.clear_caches()
def _log_likelihoods(self,x):
# NOTE: nans propagate as nans
x = np.asarray(x)
K = len(self.components)
vals = np.empty((x.shape[0],K))
for idx, c in enumerate(self.components):
vals[:,idx] = c.log_likelihood(x)
vals += self.weights.log_likelihood(np.arange(K))
return logsumexp(vals,axis=1)
def log_likelihood(self,x=None):
if x is None:
return sum(l.log_likelihood() for l in self.labels_list)
else:
assert isinstance(x,(np.ndarray,list))
if isinstance(x,list):
return sum(self.log_likelihood(d) for d in x)
else:
self.add_data(x)
return self.labels_list.pop().log_likelihood()
### parallel tempering
@property
def temperature(self):
return self._temperature if hasattr(self,'_temperature') else 1.
@temperature.setter
def temperature(self,T):
self._temperature = T
@property
def energy(self):
energy = 0.
for l in self.labels_list:
for label, datum in zip(l.z,l.data):
energy += self.components[label].energy(datum)
return energy
def swap_sample_with(self,other):
self.components, other.components = other.components, self.components
self.weights, other.weights = other.weights, self.weights
for l1, l2 in zip(self.labels_list,other.labels_list):
l1.z, l2.z = l2.z, l1.z
### Gibbs sampling
def resample_model(self,num_procs=0,components_jobs=0):
self.resample_components(num_procs=components_jobs)
self.resample_weights()
self.resample_labels(num_procs=num_procs)
def resample_weights(self):
self.weights.resample([l.z for l in self.labels_list])
self._clear_caches()
def resample_components(self,num_procs=0):
if num_procs == 0:
for idx, c in enumerate(self.components):
c.resample(data=[l.data[l.z == idx] for l in self.labels_list])
else:
self._resample_components_joblib(num_procs)
self._clear_caches()
def resample_labels(self,num_procs=0):
if num_procs == 0:
for l in self.labels_list:
l.resample()
else:
self._resample_labels_joblib(num_procs)
def copy_sample(self):
new = copy.copy(self)
new.components = [c.copy_sample() for c in self.components]
new.weights = self.weights.copy_sample()
new.labels_list = [l.copy_sample() for l in self.labels_list]
for l in new.labels_list:
l.model = new
return new
def _resample_components_joblib(self,num_procs):
from joblib import Parallel, delayed
from . import parallel_mixture
parallel_mixture.model = self
parallel_mixture.labels_list = self.labels_list
if len(self.components) > 0:
params = Parallel(n_jobs=num_procs,backend='multiprocessing')\
(delayed(parallel_mixture._get_sampled_component_params)(idx)
for idx in range(len(self.components)))
for c, p in zip(self.components,params):
c.parameters = p
def _resample_labels_joblib(self,num_procs):
from joblib import Parallel, delayed
from . import parallel_mixture
if len(self.labels_list) > 0:
parallel_mixture.model = self
raw = Parallel(n_jobs=num_procs,backend='multiprocessing')\
(delayed(parallel_mixture._get_sampled_labels)(idx)
for idx in range(len(self.labels_list)))
for l, (z,normalizer) in zip(self.labels_list,raw):
l.z, l._normalizer = z, normalizer
### Mean Field
def meanfield_coordinate_descent_step(self):
assert all(isinstance(c,MeanField) for c in self.components), \
'Components must implement MeanField'
assert len(self.labels_list) > 0, 'Must have data to run MeanField'
self._meanfield_update_sweep()
return self._vlb()
def _meanfield_update_sweep(self):
# NOTE: to interleave mean field steps with Gibbs sampling steps, label
# updates need to come first, otherwise the sampled updates will be
# ignored and the model will essentially stay where it was the last time
# mean field updates were run
# TODO fix that, seed with sample from variational distribution
self.meanfield_update_labels()
self.meanfield_update_parameters()
def meanfield_update_labels(self):
for l in self.labels_list:
l.meanfieldupdate()
def meanfield_update_parameters(self):
self.meanfield_update_components()
self.meanfield_update_weights()
def meanfield_update_weights(self):
self.weights.meanfieldupdate(None,[l.r for l in self.labels_list])
self._clear_caches()
def meanfield_update_components(self):
for idx, c in enumerate(self.components):
c.meanfieldupdate([l.data for l in self.labels_list],
[l.r[:,idx] for l in self.labels_list])
self._clear_caches()
def _vlb(self):
vlb = 0.
vlb += sum(l.get_vlb() for l in self.labels_list)
vlb += self.weights.get_vlb()
vlb += sum(c.get_vlb() for c in self.components)
for l in self.labels_list:
vlb += np.sum([r.dot(c.expected_log_likelihood(l.data))
for c,r in zip(self.components, l.r.T)])
# add in symmetry factor (if we're actually symmetric)
if len(set(type(c) for c in self.components)) == 1:
vlb += special.gammaln(len(self.components)+1)
return vlb
### SVI
def meanfield_sgdstep(self,minibatch,prob,stepsize,**kwargs):
minibatch = minibatch if isinstance(minibatch,list) else [minibatch]
mb_labels_list = []
for data in minibatch:
self.add_data(data,z=np.empty(data.shape[0]),**kwargs) # NOTE: dummy
mb_labels_list.append(self.labels_list.pop())
for l in mb_labels_list:
l.meanfieldupdate()
self._meanfield_sgdstep_parameters(mb_labels_list,prob,stepsize)
def _meanfield_sgdstep_parameters(self,mb_labels_list,prob,stepsize):
self._meanfield_sgdstep_components(mb_labels_list,prob,stepsize)
self._meanfield_sgdstep_weights(mb_labels_list,prob,stepsize)
def _meanfield_sgdstep_components(self,mb_labels_list,prob,stepsize):
for idx, c in enumerate(self.components):
c.meanfield_sgdstep(
[l.data for l in mb_labels_list],
[l.r[:,idx] for l in mb_labels_list],
prob,stepsize)
def _meanfield_sgdstep_weights(self,mb_labels_list,prob,stepsize):
self.weights.meanfield_sgdstep(
None,[l.r for l in mb_labels_list],
prob,stepsize)
### EM
def EM_step(self):
# assert all(isinstance(c,MaxLikelihood) for c in self.components), \
# 'Components must implement MaxLikelihood'
assert len(self.labels_list) > 0, 'Must have data to run EM'
## E step
for l in self.labels_list:
l.E_step()
## M step
# component parameters
for idx, c in enumerate(self.components):
c.max_likelihood([l.data for l in self.labels_list],
[l.expectations[:,idx] for l in self.labels_list])
# mixture weights
self.weights.max_likelihood(None,
[l.expectations for l in self.labels_list])
@property
def num_parameters(self):
# NOTE: scikit.learn's gmm.py doesn't count the weights in the number of
# parameters, but I don't know why they wouldn't. Some convention?
return sum(c.num_parameters for c in self.components) + self.weights.num_parameters
def BIC(self,data=None):
'''
BIC on the passed data.
If passed data is None (default), calculates BIC on the model's assigned data.
'''
# NOTE: in principle this method computes the BIC only after finding the
# maximum likelihood parameters (or, of course, an EM fixed-point as an
# approximation!)
if data is None:
assert len(self.labels_list) > 0, \
"If not passing in data, the class must already have it. Use the method add_data()"
return -2*sum(self.log_likelihood(l.data) for l in self.labels_list) + \
self.num_parameters * np.log(sum(l.data.shape[0] for l in self.labels_list))
else:
return -2*self.log_likelihood(data) + self.num_parameters * np.log(data.shape[0])
def AIC(self):
# NOTE: in principle this method computes the AIC only after finding the
# maximum likelihood parameters (or, of course, an EM fixed-point as an
# approximation!)
assert len(self.labels_list) > 0, 'Must have data to get AIC'
return 2*self.num_parameters - 2*sum(self.log_likelihood(l.data) for l in self.labels_list)
### Misc.
@property
def used_labels(self):
if len(self.labels_list) > 0:
label_usages = sum(np.bincount(l.z,minlength=self.N) for l in self.labels_list)
used_labels, = np.where(label_usages > 0)
else:
used_labels = np.argsort(self.weights.weights)[-1:-11:-1]
return used_labels
def plot(self,color=None,legend=False,alpha=None,update=False,draw=True):
import matplotlib.pyplot as plt
from matplotlib import cm
artists = []
### get colors
cmap = cm.get_cmap()
if color is None:
label_colors = dict((idx,cmap(v))
for idx, v in enumerate(np.linspace(0,1,self.N,endpoint=True)))
else:
label_colors = dict((idx,color) for idx in range(self.N))
### plot data scatter
for l in self.labels_list:
colorseq = [label_colors[label] for label in l.z]
if update and hasattr(l,'_data_scatter'):
l._data_scatter.set_offsets(l.data[:,:2])
l._data_scatter.set_color(colorseq)
else:
l._data_scatter = plt.scatter(l.data[:,0],l.data[:,1],c=colorseq,s=5)
artists.append(l._data_scatter)
### plot parameters
axis = plt.axis()
for label, (c, w) in enumerate(zip(self.components,self.weights.weights)):
artists.extend(
c.plot(
color=label_colors[label],
label='%d' % label,
alpha=min(0.25,1.-(1.-w)**2)/0.25 if alpha is None else alpha,
update=update,draw=False))
plt.axis(axis)
### add legend
if legend and color is None:
plt.legend(
[plt.Rectangle((0,0),1,1,fc=c)
for i,c in label_colors.items() if i in used_labels],
[i for i in label_colors if i in used_labels],
loc='best', ncol=2)
if draw: plt.draw()
return artists
def to_json_dict(self):
assert len(self.labels_list) == 1
data = self.labels_list[0].data
z = self.labels_list[0].z
assert data.ndim == 2 and data.shape[1] == 2
return {
'points':[{'x':x,'y':y,'label':int(label)} for x,y,label in zip(data[:,0],data[:,1],z)],
'ellipses':[dict(list(c.to_json_dict().items()) + [('label',i)])
for i,c in enumerate(self.components) if i in z]
}
def predictive_likelihoods(self,test_data,forecast_horizons):
likes = self._log_likelihoods(test_data)
return [likes[k:] for k in forecast_horizons]
def block_predictive_likelihoods(self,test_data,blocklens):
csums = np.cumsum(self._log_likelihoods(test_data))
outs = []
for k in blocklens:
outs.append(csums[k:] - csums[:-k])
return outs
class Mixture(ModelGibbsSampling, ModelMeanField, ModelEM,
ModelParallelTempering):
'''
This class is for mixtures of other distributions.
'''
_labels_class = Labels
def __init__(self,
components,
alpha_0=None,
a_0=None,
b_0=None,
weights=None,
weights_obj=None):
assert len(components) > 0
assert (alpha_0 is not None) ^ (a_0 is not None and b_0 is not None) \
^ (weights_obj is not None)
self.components = components
if alpha_0 is not None:
self.weights = Categorical(alpha_0=alpha_0,
K=len(components),
weights=weights)
elif weights_obj is not None:
self.weights = weights_obj
else:
self.weights = CategoricalAndConcentration(a_0=a_0,
b_0=b_0,
K=len(components),
weights=weights)
self.labels_list = []
def add_data(self, data, **kwargs):
self.labels_list.append(
self._labels_class(data=np.asarray(data), model=self, **kwargs))
return self.labels_list[-1]
@property
def N(self):
return len(self.components)
def generate(self, N, keep=True):
templabels = self._labels_class(model=self, N=N)
out = np.empty(self.components[0].rvs(N).shape)
counts = np.bincount(templabels.z, minlength=self.N)
for idx, (c, count) in enumerate(zip(self.components, counts)):
out[templabels.z == idx, ...] = c.rvs(count)
perm = np.random.permutation(N)
out = out[perm]
templabels.z = templabels.z[perm]
if keep:
templabels.data = out
self.labels_list.append(templabels)
return out, templabels.z
def _clear_caches(self):
for l in self.labels_list:
l.clear_caches()
def _log_likelihoods(self, x):
# NOTE: nans propagate as nans
x = np.asarray(x)
K = len(self.components)
vals = np.empty((x.shape[0], K))
for idx, c in enumerate(self.components):
vals[:, idx] = c.log_likelihood(x)
vals += self.weights.log_likelihood(np.arange(K))
return logsumexp(vals, axis=1)
def log_likelihood(self, x=None):
if x is None:
return sum(l.log_likelihood() for l in self.labels_list)
else:
assert isinstance(x, (np.ndarray, list))
if isinstance(x, list):
return sum(self.log_likelihood(d) for d in x)
else:
self.add_data(x)
return self.labels_list.pop().log_likelihood()
### parallel tempering
@property
def temperature(self):
return self._temperature if hasattr(self, '_temperature') else 1.
@temperature.setter
def temperature(self, T):
self._temperature = T
@property
def energy(self):
energy = 0.
for l in self.labels_list:
for label, datum in zip(l.z, l.data):
energy += self.components[label].energy(datum)
return energy
def swap_sample_with(self, other):
self.components, other.components = other.components, self.components
self.weights, other.weights = other.weights, self.weights
for l1, l2 in zip(self.labels_list, other.labels_list):
l1.z, l2.z = l2.z, l1.z
### Gibbs sampling
def resample_model(self, num_procs=0, components_jobs=0):
self.resample_components(num_procs=components_jobs)
self.resample_weights()
self.resample_labels(num_procs=num_procs)
def resample_weights(self):
self.weights.resample([l.z for l in self.labels_list])
self._clear_caches()
def resample_components(self, num_procs=0):
if num_procs == 0:
for idx, c in enumerate(self.components):
c.resample(data=[l.data[l.z == idx] for l in self.labels_list])
else:
self._resample_components_joblib(num_procs)
self._clear_caches()
def resample_labels(self, num_procs=0):
if num_procs == 0:
for l in self.labels_list:
l.resample()
else:
self._resample_labels_joblib(num_procs)
def copy_sample(self):
new = copy.copy(self)
new.components = [c.copy_sample() for c in self.components]
new.weights = self.weights.copy_sample()
new.labels_list = [l.copy_sample() for l in self.labels_list]
for l in new.labels_list:
l.model = new
return new
def _resample_components_joblib(self, num_procs):
from joblib import Parallel, delayed
from . import parallel_mixture
parallel_mixture.model = self
parallel_mixture.labels_list = self.labels_list
if len(self.components) > 0:
params = Parallel(n_jobs=num_procs,backend='multiprocessing')\
(delayed(parallel_mixture._get_sampled_component_params)(idx)
for idx in range(len(self.components)))
for c, p in zip(self.components, params):
c.parameters = p
def _resample_labels_joblib(self, num_procs):
from joblib import Parallel, delayed
from . import parallel_mixture
if len(self.labels_list) > 0:
parallel_mixture.model = self
raw = Parallel(n_jobs=num_procs,backend='multiprocessing')\
(delayed(parallel_mixture._get_sampled_labels)(idx)
for idx in range(len(self.labels_list)))
for l, (z, normalizer) in zip(self.labels_list, raw):
l.z, l._normalizer = z, normalizer
### Mean Field
def meanfield_coordinate_descent_step(self):
assert all(isinstance(c,MeanField) for c in self.components), \
'Components must implement MeanField'
assert len(self.labels_list) > 0, 'Must have data to run MeanField'
self._meanfield_update_sweep()
return self._vlb()
def _meanfield_update_sweep(self):
# NOTE: to interleave mean field steps with Gibbs sampling steps, label
# updates need to come first, otherwise the sampled updates will be
# ignored and the model will essentially stay where it was the last time
# mean field updates were run
# TODO fix that, seed with sample from variational distribution
self.meanfield_update_labels()
self.meanfield_update_parameters()
def meanfield_update_labels(self):
for l in self.labels_list:
l.meanfieldupdate()
def meanfield_update_parameters(self):
self.meanfield_update_components()
self.meanfield_update_weights()
def meanfield_update_weights(self):
self.weights.meanfieldupdate(None, [l.r for l in self.labels_list])
self._clear_caches()
def meanfield_update_components(self):
for idx, c in enumerate(self.components):
c.meanfieldupdate([l.data for l in self.labels_list],
[l.r[:, idx] for l in self.labels_list])
self._clear_caches()
def _vlb(self):
vlb = 0.
vlb += sum(l.get_vlb() for l in self.labels_list)
vlb += self.weights.get_vlb()
vlb += sum(c.get_vlb() for c in self.components)
for l in self.labels_list:
vlb += np.sum([
r.dot(c.expected_log_likelihood(l.data))
for c, r in zip(self.components, l.r.T)
])
# add in symmetry factor (if we're actually symmetric)
if len(set(type(c) for c in self.components)) == 1:
vlb += special.gammaln(len(self.components) + 1)
return vlb
### SVI
def meanfield_sgdstep(self, minibatch, prob, stepsize, **kwargs):
minibatch = minibatch if isinstance(minibatch, list) else [minibatch]
mb_labels_list = []
for data in minibatch:
self.add_data(data, z=np.empty(data.shape[0]),
**kwargs) # NOTE: dummy
mb_labels_list.append(self.labels_list.pop())
for l in mb_labels_list:
l.meanfieldupdate()
self._meanfield_sgdstep_parameters(mb_labels_list, prob, stepsize)
def _meanfield_sgdstep_parameters(self, mb_labels_list, prob, stepsize):
self._meanfield_sgdstep_components(mb_labels_list, prob, stepsize)
self._meanfield_sgdstep_weights(mb_labels_list, prob, stepsize)
def _meanfield_sgdstep_components(self, mb_labels_list, prob, stepsize):
for idx, c in enumerate(self.components):
c.meanfield_sgdstep([l.data for l in mb_labels_list],
[l.r[:, idx] for l in mb_labels_list], prob,
stepsize)
def _meanfield_sgdstep_weights(self, mb_labels_list, prob, stepsize):
self.weights.meanfield_sgdstep(None, [l.r for l in mb_labels_list],
prob, stepsize)
### EM
def EM_step(self):
# assert all(isinstance(c,MaxLikelihood) for c in self.components), \
# 'Components must implement MaxLikelihood'
assert len(self.labels_list) > 0, 'Must have data to run EM'
## E step
for l in self.labels_list:
l.E_step()
## M step
# component parameters
for idx, c in enumerate(self.components):
c.max_likelihood(
[l.data for l in self.labels_list],
[l.expectations[:, idx] for l in self.labels_list])
# mixture weights
self.weights.max_likelihood(None,
[l.expectations for l in self.labels_list])
@property
def num_parameters(self):
# NOTE: scikit.learn's gmm.py doesn't count the weights in the number of
# parameters, but I don't know why they wouldn't. Some convention?
return sum(c.num_parameters
for c in self.components) + self.weights.num_parameters
def BIC(self, data=None):
'''
BIC on the passed data.
If passed data is None (default), calculates BIC on the model's assigned data.
'''
# NOTE: in principle this method computes the BIC only after finding the
# maximum likelihood parameters (or, of course, an EM fixed-point as an
# approximation!)
if data is None:
assert len(self.labels_list) > 0, \
"If not passing in data, the class must already have it. Use the method add_data()"
return -2*sum(self.log_likelihood(l.data) for l in self.labels_list) + \
self.num_parameters * np.log(sum(l.data.shape[0] for l in self.labels_list))
else:
return -2 * self.log_likelihood(
data) + self.num_parameters * np.log(data.shape[0])
def AIC(self):
# NOTE: in principle this method computes the AIC only after finding the
# maximum likelihood parameters (or, of course, an EM fixed-point as an
# approximation!)
assert len(self.labels_list) > 0, 'Must have data to get AIC'
return 2 * self.num_parameters - 2 * sum(
self.log_likelihood(l.data) for l in self.labels_list)
### Misc.
@property
def used_labels(self):
if len(self.labels_list) > 0:
label_usages = sum(
np.bincount(l.z, minlength=self.N) for l in self.labels_list)
used_labels, = np.where(label_usages > 0)
else:
used_labels = np.argsort(self.weights.weights)[-1:-11:-1]
return used_labels
def plot(self,
color=None,
legend=False,
alpha=None,
update=False,
draw=True):
import matplotlib.pyplot as plt
from matplotlib import cm
artists = []
### get colors
cmap = cm.get_cmap()
if color is None:
label_colors = dict((idx, cmap(v)) for idx, v in enumerate(
np.linspace(0, 1, self.N, endpoint=True)))
else:
label_colors = dict((idx, color) for idx in range(self.N))
### plot data scatter
for l in self.labels_list:
colorseq = [label_colors[label] for label in l.z]
if update and hasattr(l, '_data_scatter'):
l._data_scatter.set_offsets(l.data[:, :2])
l._data_scatter.set_color(colorseq)
else:
l._data_scatter = plt.scatter(l.data[:, 0],
l.data[:, 1],
c=colorseq,
s=5)
artists.append(l._data_scatter)
### plot parameters
axis = plt.axis()
for label, (c,
w) in enumerate(zip(self.components,
self.weights.weights)):
artists.extend(
c.plot(color=label_colors[label],
label='%d' % label,
alpha=min(0.25, 1. - (1. - w)**2) /
0.25 if alpha is None else alpha,
update=update,
draw=False))
plt.axis(axis)
### add legend
if legend and color is None:
plt.legend([
plt.Rectangle((0, 0), 1, 1, fc=c)
for i, c in label_colors.items() if i in used_labels
], [i for i in label_colors if i in used_labels],
loc='best',
ncol=2)
if draw: plt.draw()
return artists
def to_json_dict(self):
assert len(self.labels_list) == 1
data = self.labels_list[0].data
z = self.labels_list[0].z
assert data.ndim == 2 and data.shape[1] == 2
return {
'points': [{
'x': x,
'y': y,
'label': int(label)
} for x, y, label in zip(data[:, 0], data[:, 1], z)],
'ellipses': [
dict(list(c.to_json_dict().items()) + [('label', i)])
for i, c in enumerate(self.components) if i in z
]
}
def predictive_likelihoods(self, test_data, forecast_horizons):
likes = self._log_likelihoods(test_data)
return [likes[k:] for k in forecast_horizons]
def block_predictive_likelihoods(self, test_data, blocklens):
csums = np.cumsum(self._log_likelihoods(test_data))
outs = []
for k in blocklens:
outs.append(csums[k:] - csums[:-k])
return outs
