with pm.Model() as model_1:
mu_A = pm.Normal("mu_A", pooled_mean, sd = variance)
mu_B = pm.Normal("mu_B", pooled_mean, sd = variance)
std_A = pm.Uniform("std_A", 1/100, 100)
std_B = pm.Uniform("std_B", 1/100, 100)
nu_minus_1 = pm.Exponential("nu-1", 1.0/29)
# In[13]:
with model_1:
obs_A = pm.StudentT("obs_A", mu = mu_A, lam = 1.0/std_A**2, nu = nu_minus_1+1, observed = Control_Matrix.Pvs_per_session)
obs_B = pm.StudentT("obs_B", mu = mu_B, lam = 1.0/std_B**2, nu = nu_minus_1+1, observed = Variant_BT.Pvs_per_session)
start = pm.find_MAP()
step = pm.Metropolis(vars=[mu_A, mu_B, std_A, std_B, nu_minus_1])
trace_1 = pm.sample(25000, step=step)
burned_trace_1 = trace_1[10000:]
# You can now visualise the posterior distribution of the group means:
# In[14]:
figsize(12.5, 4)
control_mean = burned_trace_1['mu_A']
variant_mean = burned_trace_1['mu_B']
plt.hist(control_mean, bins = 100, label=r'Posterior distribution of $\mu_{Control_Matrix}$', color = 'grey')
plt.hist(variant_mean, bins = 100, label=r'Posterior distribution of $\mu_{Variant_BT}$', color = 'orange')
plt.title('Posterior distributions for each respective group mean')
def bayesian_logistic(
df_,
feature_names,
target_name,
results,
participant,
experiment,
dot_dir,
window=0,
):
"""
Since the classification is redundent after the features and targets are
ready, I would rather to make a function for the redundent part
Inputs:
df_ : dataframe of a given subject
feature_names : names of features
target_name : name of target
results : dictionary like object, update itself every cross validation
participant : string, for updating the results dictionary
experiment : for graph of the tree model
dot_dit : directory of the tree plots
window : integer value, for updating the results dictionary
return:
results
"""
features, targets = [], []
for block, df_block in df_.groupby('blocks'):
# preparing the features and target by shifting the feature columns up
# and shifting the target column down
feature = (
df_block[feature_names].shift(
window) # shift downward so that the last n_back rows are gone
.dropna() # since some of rows are gone, so they are nans
.values # I only need the matrix not the data frame
)
target = (
df_block[target_name].shift(
-window
) # same thing for the target, but shifting upward, and the first n_back rows are gone
.dropna().values)
features.append(feature)
targets.append(target)
features = np.concatenate(features)
targets = np.concatenate(targets)
features, targets = shuffle(features, targets)
# for each classifier, we fit-test cross validate the classifier and save the
# classification score and the weights of the attributes
model_name = 'bayes_logistic'
# this is for initialization
df_train = pd.DataFrame(features, columns=feature_names)
df_train[target_name] = targets
scaler = StandardScaler()
for name in feature_names:
if 'RT' in name:
df_train[name] = scaler.fit_transform(
df_train[name].values.reshape(-1, 1))
niter = 1000
formula = '{} ~'.format(target_name)
for name in feature_names:
formula += ' + {}'.format(name)
with pm.Model() as model:
pm.glm.GLM.from_formula(
formula,
df_train,
family=pm.glm.families.Binomial(),
)
start = pm.find_MAP(progressbar=False)
try:
step = pm.NUTS(scaling=start, )
except:
step = pm.Metropolis()
trace = pm.sample(
niter,
start=start,
step=step,
njobs=4,
random_seed=12345,
progressbar=0,
)
df_trace = pm.trace_to_dataframe(trace[niter // 2:])
intercept = df_trace['Intercept'].mean()
df_test = pd.DataFrame(features, columns=feature_names)
weights = df_trace.iloc[:, 1:].values.mean(0)
preds = predict(df_test.values, weights, intercept)
# score the predictions
score = roc_auc_score(targets, preds)
results['sub'].append(participant)
results['model'].append(model_name)
results['score'].append(score)
results['window'].append(window)
for iii, name in enumerate(feature_names):
results[name].append(df_trace[name].values.mean())
print('sub {},model {},window {},score={:.3f}'.format(
participant, model_name, window, score))
return results, trace
# stronger beliefs could lead to different priors
p_test = pm.Uniform("p_test", 0, 1)
p_control = pm.Uniform("p_control", 0, 1)
# deterministic delta variable, our unknown of interest
# deterministic is not based on a distribution
delta = pm.Deterministic("delta", p_test - p_control)
# Set of observations
# Bernoulli stochastic variables generated via our observed values
obs_A = pm.Bernoulli("obs_A", p_test, observed=test_obs)
obs_B = pm.Bernoulli("obs_B", p_control, observed=control_obs)
# monte carlo simulation, last step of model, this part takes the longest
# metropolis-hastings algo, gets sequence of random variables from prob. dist.
step = pm.Metropolis()
trace = pm.sample(20000, step=step, njobs=2)
burned_trace = trace[10000:]
# generated likelihood, prior, and posterior distributions as arrays of values
p_test_samples = burned_trace["p_test"]
p_control_samples = burned_trace["p_control"]
delta_samples = burned_trace["delta"]
delta_min = delta_samples.min()
delta_max = delta_samples.max()
target_cann = -0.02
abs_target = (control_conv) * target_cann
# results and calculations data for DOMO
abs_target = (control_conv) * target_cann
prob_cann = 100 - (round(
def test_run(self):
with self.build_model():
pm.sample(50, step=[pm.NUTS(), pm.Metropolis()])
S2=S2,
states=states1,
observed = dataset[4])
states2 = HMMStatesN('states2',P=P,PA=PA, shape=len(dataset[205]))
emission2 = HMMGaussianEmissions('emission2',
A1=A1,
A2=A1,
S1=S1,
S2=S2,
states=states2,
observed = dataset[205])
start = pm.find_MAP(fmin=optimize.fmin_powell)
step1 = pm.Metropolis(vars=[P, PA, A1, A2, S1, S2, emission1,emission2])
step2 = pm.BinaryGibbsMetropolis(vars=[states1,states2])
trace = pm.sample(10000, start=start, step=[step1, step2])
pm.traceplot(trace)
pm.summary(trace[500:])
sample1_avg=np.average(trace['states1'][500:],axis=0)
sample2_avg=np.average(trace['states2'][500:],axis=0)
plt.figure()
plt.plot(dataset[4])
plt.plot((sample1_avg)*0.6)
plt.figure()
plt.plot(dataset[205])
def outlier_detection(data, uncertainties):
#Outlier detection
#This follows the analysis from Hogg, Bovy and Lang (2010): https://arxiv.org/pdf/1008.4686.pdf
#And is edited slightly from the pymc3 tutorial
#here: https://docs.pymc.io/notebooks/GLM-robust-with-outlier-detection.html
with pm.Model() as mdl_signoise:
sig_hyperprior = pm.Uniform('sig', 0.0, 50.0)
vel_hyperprior = pm.Normal('vel', 0.0, 50.0)
vel_tracers = pm.Normal('vel-tracers',
mu=vel_hyperprior,
sd=uncertainties,
shape=len(data))
## Define weakly informative priors for the mean and variance of outliers
vel_out = pm.Normal('vel-out', mu=0, sd=100, testval=pm.floatX(1.))
sig_out = pm.HalfNormal('sig-out', sd=100, testval=pm.floatX(1.))
## Define Bernoulli inlier / outlier flags according to a hyperprior
## fraction of outliers, itself constrained to [0,.5] for symmetry
frac_outliers = pm.Uniform('frac-outliers', lower=0., upper=.5)
is_outlier = pm.Bernoulli('is-outlier',
p=frac_outliers,
shape=len(data))
## Extract observed y and sigma_y from dataset, encode as theano objects
data_thno = thno.shared(np.asarray(data, dtype=thno.config.floatX),
name='data')
uncert_thno = thno.shared(np.asarray(uncertainties,
dtype=thno.config.floatX),
name='uncertainties')
## Use custom likelihood using DensityDist
likelihood = pm.DensityDist('likelihood',
logp_signoise,
observed={
'data': data_thno,
'isoutlier': is_outlier,
'velin': vel_tracers,
'sigin': sig_hyperprior,
'velout': vel_out,
'sigout': sig_out
})
with mdl_signoise:
## two-step sampling to create Bernoulli inlier/outlier flags
step1 = pm.Metropolis([frac_outliers, vel_out, sig_out])
step2 = pm.step_methods.BinaryGibbsMetropolis([is_outlier])
## take samples
# I got an error when njob>1 here. Not sure why!
traces_signoise = pm.sample(20000,
step=[step1, step2],
tune=10000,
progressbar=True,
njobs=1)
#Plot things
pm.traceplot(traces_signoise)
plt.savefig('Plots/outlier_traceplot.pdf')
index = np.arange(1, len(data) + 1)
fig, ax = plt.subplots(figsize=(10, 6))
mean_outlier_prob = np.mean(traces_signoise['is-outlier'][-1000:, :],
axis=0)
ax.scatter(mean_outlier_prob, index)
ax.set_yticks(index)
ax.set_yticklabels(["{} km/s".format(int(d)) for d in data])
for i in index:
ax.axhline(i, c='k', alpha=0.1, linestyle='dashed')
ax.set_title('Outlier Probabilities')
ax.set_xlabel(r'$p_{\mathrm{outlier}}$')
ax.set_ylabel('Data point')
fig.tight_layout()
fig.savefig('Plots/outlier_probabilities.pdf')
#KDE approximation to the new posterior
xx = np.linspace(0.0, 30.0, 1000)
kde_approximation2 = stats.gaussian_kde(traces_signoise['sig'])
fig, ax = plt.subplots(figsize=(10, 6))
ax.plot(xx, kde_approximation2(xx), c='r', linewidth=3.0)
ax.hist(traces_signoise['sig'],
100,
facecolor='0.8',
edgecolor='k',
histtype='stepfilled',
normed=True,
linewidth=2.0)
ax.axvline(xx[np.argmax(kde_approximation2(xx))],
c='k',
linestyle='dashed',
linewidth=2.0)
ax.set_title(r'$\sigma$- with outlier detection')
ax.set_xlim([0.0, 30.0])
ax.set_ylabel(r'PDF')
ax.set_yticks([])
#ax.tick_params(axis='both', which='major', labelsize=15)
ax.set_xlabel(r'$\sigma$ (kms$^{-1}$)')
fig.tight_layout()
fig.savefig('Plots/pdf_outliers.jpg')
return kde_approximation2
mix = np.random.normal(np.repeat(means, n_cluster),
np.repeat(std_devs, n_cluster))
with pm.Model() as model_ug:
# Each observation is assigned to a cluster/component with probability p
p = pm.Dirichlet('p', a=np.ones(clusters))
category = pm.Categorical('category', p=p, shape=n_total)
# We estimate the unknown gaussians means and standard deviation
means = pm.Normal('means', mu=[10, 20, 35], sd=2, shape=clusters)
sd = pm.HalfCauchy('sd', 5)
y = pm.Normal('y', mu=means[category], sd=sd, observed=mix)
step1 = pm.ElemwiseCategorical(vars=[category], values=range(clusters))
step2 = pm.Metropolis(vars=[means, sd, p])
trace_ug = pm.sample(10000, step=[step1, step2], nchains=1)
chain_ug = trace_ug[1000:]
pm.traceplot(chain_ug)
plt.figure()
ppc = pm.sample_ppc(chain_ug, 50, model_ug)
for i in ppc['y']:
sns.kdeplot(i, alpha=0.1, color='b')
sns.kdeplot(
np.array(mix), lw=2,
color='k') # you may want to replace this with the posterior mean
plt.xlabel('$x$', fontsize=14)
with add_prefix(f'Process #{rank}'):
dat, err = ss
ell, pol = bs
print('Initializing model.')
model = sed2.fg_models.init(model_name, dat, err, ac, map_coll,
do_sim)
with model: # pymc3 wants the model object in the context stack when running things
# Also, don't try to split into multiple processes, because it probably won't help given MPI is around
print('Sampling with model.')
if step == 'metropolis':
trace = pymc.sample(10000,
tune=1000,
chains=2,
step=pymc.Metropolis(),
progressbar=False,
return_inferencedata=False)
elif step == 'None':
trace = pymc.sample(10000,
tune=1000,
chains=2,
progressbar=False,
return_inferencedata=False)
else:
raise NameError('Unknown step method.')
file_write(ell, pol, trace, post_dir)
file_write(ell, pol + '_model', model, post_dir)
else: # These models fit over ell, so only split by pol
predictorNames = x.columns
n_predictors = len(predictorNames)
# THE MODEL
with pm.Model() as model:
# define the priors
beta0 = pm.Normal('beta0', mu=0, tau=1.0E-12)
beta1 = pm.Normal('beta1', mu=0, tau=1.0E-12, shape=n_predictors)
tau = pm.Gamma('tau', 0.01, 0.01)
mu = beta0 + pm.dot(beta1, x.values.T)
# define the likelihood
yl = pm.Normal('yl', mu=mu, tau=tau, observed=y)
# Generate a MCMC chain
start = pm.find_MAP()
step1 = pm.NUTS([beta1])
step2 = pm.Metropolis([beta0, tau])
trace = pm.sample(10000, [step1, step2], start, progressbar=False)
# EXAMINE THE RESULTS
burnin = 5000
thin = 1
# Print summary for each trace
#pm.summary(trace[burnin::thin])
#pm.summary(trace)
# Check for mixing and autocorrelation
#pm.autocorrplot(trace[burnin::thin], vars =[mu, tau])
#pm.autocorrplot(trace, vars =[beta0])
## Plot KDE and sampled values for each parameter.
def fit(
self,
draws: int = 500,
chains: int = 4,
trace_size: int = 500,
method: Sampler = Sampler.NUTS,
map_initialization: bool = False,
finalize: bool = True,
step_kwargs: Dict = None,
sample_kwargs: Dict = None,
):
"""Fit the PMProphet model.
Parameters
----------
draws : int, > 0
The number of MCMC samples.
chains: int, =4
The number of MCMC draws.
trace_size: int, =1000
The last N number of samples to keep in the trace
method : Sampler
The sampler of your choice
map_initialization : bool
Initialize the model with maximum a posteriori estimates.
finalize : bool
Finalize the model.
step_kwargs : dict
Additional arguments for the sampling algorithms
(`NUTS` or `Metropolis`).
sample_kwargs : dict
Additional arguments for the PyMC3 `sample` function.
"""
if sample_kwargs is None:
sample_kwargs = {}
if step_kwargs is None:
step_kwargs = {}
if chains * draws < trace_size and method != Sampler.ADVI:
raise Exception(
"Desired trace size should be smaller than the sampled data points"
)
self.skip_first = (chains *
draws) - trace_size if method != Sampler.ADVI else 0
self.chains = chains
if finalize:
self.finalize_model()
with self.model:
if map_initialization:
self.start = pm.find_MAP(maxeval=10000)
if draws == 0:
self.trace = {
k: np.array([v])
for k, v in self.start.items()
}
if draws:
if method in (Sampler.NUTS, Sampler.METROPOLIS):
step_method = pm.NUTS(
**step_kwargs
) if method == Sampler.NUTS else pm.Metropolis(
**step_kwargs)
self.trace = pm.sample(
draws,
chains=chains,
step=step_method,
start=self.start if map_initialization else None,
**sample_kwargs)
elif method == Sampler.ADVI:
res = pm.fit(
draws,
start=self.start if map_initialization else None)
self.trace = res.sample(trace_size)
"""
Reimplementation of Rate_1 model from Chapter 3, Bayesian Cognitive Modeling.
Created Aug/2015 by Johannes Keyser <*****@*****.**>
"""
import pymc3 as pm
n = 100 # n = 10, or n = 100, or k = 0
k = 50 # k = 5, or k = 99, or n = 1
# For n=100, k=50, theta's posterior gets more narrow, b/c more data.
# For n=100, k=99, theta's posterior narrows down further, and gets almost
# squeezed against its maximum, where it drops abruptly.
# For n=1, k=0, theta's posterior is still very broad, but clearly leans toward
# lower values. Even one data point can have a lot of influence.
model = pm.Model()
with model:
# Prior Distribution for Rate Theta
theta = pm.Beta('theta', alpha=1, beta=1)
# Observed Counts
k = pm.Binomial('k', p=theta, n=n, observed=k)
# instantiate Metropolis-Hastings sampler
stepFunc = pm.Metropolis()
# draw 20,000 posterior samples (in 2 parallel chains)
Nsample = 10000
traces = pm.sample(Nsample, step=stepFunc, njobs=2)
axs = pm.traceplot(traces, vars=['theta'], combined=False)
axs[0][0].set_xlim([0, 1]) # manually set x-limits for comparisons
def MCMC_THEANO(data, path_model, train=True, samples=2000):
model_fit = Path(path_model)
# Comprobamos si ya existe un archivo con el modelo entrenado
if model_fit.is_file():
file = open(path_model, "rb")
samples = pickle.load(file)
else:
C = data['C']
N = data['N']
A = data['A']
# Definimos el constructor para el modelo
model = pm.Model()
with model:
# Parámetros dependientes de las variables observadas
K = pm.Normal("K", mu=0, sigma=1, shape=(1, N))
gpa0 = pm.Normal("gpa0", mu=0, sigma=1)
lsat0 = pm.Normal("lsat0", mu=0, sigma=1)
w_k_gpa = pm.Normal("w_k_gpa", mu=0, sigma=1)
w_k_lsat = pm.Normal("w_k_lsat", mu=0, sigma=1)
w_k_fya = pm.Normal("w_k_fya", mu=0, sigma=1)
w_a_gpa = pm.Normal("w_a_gpa",
mu=np.zeros(C),
sigma=np.ones(C),
shape=C)
w_a_lsat = pm.Normal("w_a_lsat",
mu=np.zeros(C),
sigma=np.ones(C),
shape=C)
w_a_fya = pm.Normal("w_a_fya",
mu=np.zeros(C),
sigma=np.ones(C),
shape=C)
sigma_gpa_2 = pm.InverseGamma("sigma_gpa_2", alpha=1, beta=1)
mu = gpa0 + (w_k_gpa * K) + pm.math.dot(A, w_a_gpa)
# Definidos las variables observadas
gpa = pm.Normal("gpa",
mu=mu,
sigma=pm.math.sqrt(sigma_gpa_2),
observed=list(data["GPA"]),
shape=(1, N))
lsat = pm.Poisson("lsat",
pm.math.exp(lsat0 + w_k_lsat * K +
pm.math.dot(A, w_a_lsat)),
observed=list(data["LSAT"]),
shape=(1, N))
if train:
fya = pm.Normal("fya",
mu=w_k_fya * K + pm.math.dot(A, w_a_fya),
sigma=1,
observed=list(data["FYA"]),
shape=(1, N))
step = pm.Metropolis()
samples = pm.sample(samples, step)
# Guardamos el modelo entrenado
file = open(path_model, "wb")
pickle.dump(samples, file, protocol=-1)
return samples
def bayesian_linear_model(data,
N_steps=20000,
step="Metropolis",
burnin=None,
njobs=1,
progressbar=True,
chain_start=0,
output_format="rho",
sample_params={}):
"""Docstring for bayesian linear model.
:data: The data used, expects a 2-d array with one dimension having 2 columns/rows
:N_steps: The number of steps in each chain. If using NUTS sampling, this can be smaller.
:step: The sampling method. Either "Metropolis" (faster sampling, but needs more steps) or NUTS (slower, but fewer steps)
:burnin: number of steps to discard at the beginning of each chain. If None, half of N_steps is discarded.
:njobs: The number of parallel jobs.
:chain_start: The number assigned to the chain. Can be useful when aiming to combine different chains
:progressbar: Should a progressbar for the sampling?
:output_format: What should be returned from the sampling? If "rho" only an numpy array with the correlation
values is returned. If "full" the whole multitrace is returned, which is useful for convergence analysis.
:sample_params: Additional parameters for pymc3's sample function.
:returns: Either a multitrace or a numpy array, depending on output_format
"""
# test the data for the right format and transform it if necessary/possible
if isinstance(data, list):
try:
data = np.vstack(data)
except ValueError:
print("Error: Data dimensions do not match!")
return None
if isinstance(data, np.ndarray):
if len(data.shape) != 2:
if len(data) == 2 and len(data[0]) != len(data[1]):
print("Error: Data dimensions do not match!")
return None
else:
print(
"Error: Data not a two-dimensional array, don't know what to do!"
)
return None
else:
if data.shape[1] != 2:
if data.shape[0] != 2:
print(
"Error: No dimension with 2 variables present, don't know what to do!"
)
else:
data = data.T
# if no burnin is specified, use half of the step number
if burnin is None:
burnin = N_steps / 2
sample_params.update({
"draws": N_steps,
"njobs": njobs,
"tune": burnin,
"progressbar": progressbar
})
# initialize model
basic_model = pm.Model()
with basic_model:
# define model priors
m_mu = pm.Normal('mu', mu=0., sd=10, shape=2)
nu = pm.Uniform('nu', 0, 5)
packed_L = pm.LKJCholeskyCov('packed_L',
n=2,
eta=nu,
sd_dist=pm.HalfCauchy.dist(1.))
chol = pm.expand_packed_triangular(2, packed_L)
sigma = pm.Deterministic('sigma', _Cov2Cor(chol.dot(chol.T)))
# model likelihood
mult_n = pm.MvNormal('mult_n', mu=m_mu, chol=chol, observed=data)
# which sampler to use
if step == "Metropolis":
step = pm.Metropolis()
elif step == "NUTS":
step = pm.NUTS()
sample_params.update({"step": step})
# MCMC sample
trace = pm.sample(**sample_params)
# Return the full pymc3 trace or only an array of the correlation?
if output_format == "full":
output = trace
else:
output = trace["sigma"][:, 0, 1]
return output
def get_changepoints_location(self, n_changepoints:int) -> 'changepoint locations, list':
"""Purpose: get most likely changepoint locations given
data and number of changepoints.
Heavily inspired by:
http://www.claudiobellei.com/2017/01/25/changepoint-bayesian/
"""
if len(self.data) < 10:
raise ValueError("Received less than 10 data points!")
if n_changepoints < 1:
raise ValueError("Number of changepoints must be positive integer!")
# dictionary of means
self.mu_d = {}
# stochastic means
self.mus_d = {}
# dictionary of changepoints
self.tau_d = {}
# define time range
t = np.arange(len(self.data))
with pm.Model() as model:
# variance
#sigma = pm.Uniform("sigma",1.e-3,20)
sigma = pm.HalfNormal('sigma', sd=1)
# define means
for i in range(n_changepoints+1):
self.mu_d['mu_{0}'.format(i)] = pm.Uniform('mu_{0}'.format(i), lower=self.data.min(),
upper=self.data.max(),)# testval=int(len(self.data)/(n_changepoints+1)*(i+1)))
# define changepoint locations and stochastic variable(s) _mu
for i in (range(n_changepoints)):
if i == 0:
self.tau_d['tau_{0}'.format(i)] = pm.DiscreteUniform('tau_{0}'.format(i),
t.min(), t.max())
self.mus_d['mus_d_{0}'.format(i)] = T.switch(self.tau_d['tau_{0}'.format(i)] >= t,
self.mu_d['mu_{0}'.format(i)],
self.mu_d['mu_{0}'.format(i+1)])
else:
self.tau_d['tau_{0}'.format(i)] = pm.DiscreteUniform('tau_{0}'.format(i),
self.tau_d['tau_{0}'.format(i-1)], t.max())
self.mus_d['mus_d_{0}'.format(i)] = T.switch(self.tau_d['tau_{0}'.format(i)] >= t,
self.mus_d['mus_d_{0}'.format(i-1)],
self.mu_d['mu_{0}'.format(i+1)])
def logp_func(data):
"""Function to be provided to PyMC3
"""
return logp.sum()
# define log-likelihood for the parameters given data
logp = - T.log(sigma * T.sqr(2.0 * np.pi)) \
- T.sqr(self.data - self.mus_d['mus_d_{0}'.format(i)]) / (2.0 * sigma * sigma)
# define density dist
L_obs = pm.DensityDist('L_obs', logp_func, observed=self.data)
# start MCMC algorithm
start = pm.find_MAP()
step = pm.Metropolis()
# iterate MCMC
trace = pm.sample(self.n_iter, step, start=start, random_seed=123, progressbar=False)
# calculate changepoints
locations = []
for k in range(n_changepoints):
changepoint = Counter(trace.get_values('tau_{0}'.format(k))).most_common(1)[0][0]
locations.append(changepoint)
return sorted(set(locations)), trace
with model:
mc.Normal('X', mu, 1 / sigma**2)
# In[15]:
model.vars
# In[16]:
start = dict(X=2)
# In[17]:
with model:
step = mc.Metropolis()
trace = mc.sample(10000, step=step, start=start)
# In[18]:
x = np.linspace(-4, 12, 1000)
# In[19]:
y = stats.norm(mu, sigma).pdf(x)
# In[20]:
X = trace.get_values("X")
# In[21]:
import numpy as np
import pymc3 as pm
import scipy.stats as st
import matplotlib.pyplot as plt
from scipy.integrate import quad
obs = [-4.]
niter = 5000
nburn = 2000
nchains = 3
with pm.Model() as model:
m = pm.Uniform('m', lower=0., upper=10.)
likelihood = pm.Normal('y_obs', mu=m, sigma=2., observed=obs)
step_0 = pm.Metropolis(S=np.array([.01]))
step_1 = pm.Metropolis(S=np.array([10]))
step_2 = pm.Metropolis(S=np.array([2.5]))
trace_0 = pm.sample(niter,
step=step_0,
cores=1,
tune=0,
chains=nchains,
random_seed=123)
trace_1 = pm.sample(niter,
step=step_1,
cores=1,
tune=0,
chains=nchains,
random_seed=123)
trace_2 = pm.sample(niter,
step=step_2,
cores=1,
# Prior for distribution of switchpoint location
switchpoint = pm.DiscreteUniform('switchpoint', lower=0, upper=years)
# Priors for pre- and post-switch mean number of disasters
early_mean = pm.Exponential('early_mean', lam=1.)
late_mean = pm.Exponential('late_mean', lam=1.)
# Allocate appropriate Poisson rates to years before and after current
# switchpoint location
idx = arange(years)
# theano style:
# rate = switch(switchpoint >= idx, early_mean, late_mean)
# non-theano style
rate = rateFunc(switchpoint, early_mean, late_mean)
# Data likelihood
disasters = pm.Poisson('disasters', rate, observed=disasters_data)
# Initial values for stochastic nodes
start = {'early_mean': 2., 'late_mean': 3.}
# Use slice sampler for means
step1 = pm.Slice([early_mean, late_mean])
# Use Metropolis for switchpoint, since it accomodates discrete variables
step2 = pm.Metropolis([switchpoint])
# njobs>1 works only with most recent (mid August 2014) Theano version:
# https://github.com/Theano/Theano/pull/2021
tr = pm.sample(1000, tune=500, start=start, step=[step1, step2], njobs=1)
pm.traceplot(tr)
phic = pm.Uniform('phic', lower=0, upper=1, testval=.3)
zck = pm.Bernoulli('zck', p=phic, shape=companyABC.shape)
# zij_ = pm.theanof.tt_rng().uniform(size=xij.shape)
# zij = pm.Deterministic('zij', tt.lt(zij_, phii[sbjid]))
line = tt.constant(np.ones((len(companyABC))) * .5)
beta_mu = pm.Deterministic(
'beta_mu', tt.squeeze(tt.switch(tt.eq(zck, 0), liner, line)))
Observed = pm.Weibull("Observed",
alpha=alpha,
beta=beta_mu,
observed=elec_faults) # 观测值
# start = pm.find_MAP()
step = pm.Metropolis([zck])
# step1 = pm.Slice([am0, am1])
trace = pm.sample(4000, step=[step], init='advi+adapt_diag', tune=1000)
# with model1:
# s = shared(pm.floatX(1))
# inference = pm.ADVI(cost_part_grad_scale=s)
# # ADVI has nearly converged
# inference.fit(n=20000)
# # It is time to set `s` to zero
# s.set_value(0)
# approx = inference.fit(n=10000)
# trace = approx.sample(3000, include_transformed=True)
# elbos1 = -inference.hist
chain = trace[2000:]
mu1 = pm.Beta('mu1', 1, 1, shape=n_cond)
a_Beta1 = mu1[cond_of_subj] * kappa[cond_of_subj]
b_Beta1 = (1 - mu1[cond_of_subj]) * kappa[cond_of_subj]
#Prior on theta
theta0 = pm.Beta('theta0', a_Beta0, b_Beta0, shape=n_subj)
theta1 = pm.Beta('theta1', a_Beta1, b_Beta1, shape=n_subj)
# if model_index == 0 then sample from theta1 else sample from theta0
theta = pm.switch(pm.eq(model_index, 0), theta1, theta0)
# Likelihood:
y = pm.Binomial('y', p=theta, n=n_trl_of_subj, observed=n_corr_of_subj)
# Sampling
start = pm.find_MAP()
step1 = pm.Metropolis(model.vars[1:])
step2 = pm.ElemwiseCategoricalStep(var=model_index, values=[0, 1])
trace = pm.sample(20000, [step1, step2], start=start, progressbar=False)
# EXAMINE THE RESULTS.
burnin = 10000
thin = 10
## Print summary for each trace
#pm.summary(trace[burnin::thin])
#pm.summary(trace)
## Check for mixing and autocorrelation
#pm.autocorrplot(trace, vars =[mu, kappa])
## Plot KDE and sampled values for each parameter.
import pymc3 as pm
with pm.Model() as model:
x = pm.Normal('x', 1, 1)
x2 = pm.Potential('x2', -x**2)
start = model.test_point
h = pm.find_hessian(start)
step = pm.Metropolis(model.vars, h)
def run(n=3000):
if n == "short":
n = 50
with model:
pm.sample(n, step=step, start=start)
if __name__ == '__main__':
run()
def make_step(cls):
args = {}
if hasattr(cls, 'step_args'):
args.update(cls.step_args)
return pm.Metropolis(**args)
def run(n=1000):
if n == "short":
n = 50
with model:
trace = pm.sample(10000, step=[pm.NUTS(), pm.Metropolis()])
%config InlineBackend.figure_format = 'retina'
%matplotlib inline
plt.rcParams["figure.figsize"] = (10, 5)
np.random.seed(42)
# Prepare the data
x = uniform(0, 20).rvs(30)
eps = norm(0, 4).rvs(30)
y = 11 + 3*x + eps
# Sampling w/ Metropolis
with pm.Model() as model:
b_0 = pm.Normal("b_0", mu=0, sd=10)
b_1 = pm.Normal("b_1", mu=0, sd=2)
e = pm.HalfCauchy("e", 2)
mu = pm.Deterministic("mu", b_0 + b_1*x)
Y = pm.Normal("Y", mu=mu, sd=e, observed=y)
trace = pm.sample(10000, step=pm.Metropolis())
pm.autocorrplot(trace, varnames=["b_0", "b_1", "e"]);
plt.savefig("./results/4-12-autocorrelation-metropolis.png")
# Sampling w/ NUTS
with pm.Model() as model:
b_0 = pm.Normal("b_0", mu=0, sd=10)
b_1 = pm.Normal("b_1", mu=0, sd=2)
e = pm.HalfCauchy("e", 2)
mu = pm.Deterministic("mu", b_0 + b_1*x)
Y = pm.Normal("Y", mu=mu, sd=e, observed=y)
trace = pm.sample(10000)
pm.autocorrplot(trace, varnames=["b_0", "b_1", "e"]);
plt.savefig("./results/4-12-autocorrelation-nuts.png")
a1 = pm.Normal('a1', mu=0, tau=a1tau, shape=Nx1Lvl)
a2 = pm.Normal('a2', mu=0, tau=a2tau, shape=Nx2Lvl)
a1a2 = pm.Normal('a1a2', mu=0, tau=a1a2tau, shape=[Nx1Lvl, Nx2Lvl])
b1 = pm.Deterministic('b1', a1 - T.mean(a1))
b2 = pm.Deterministic('b2', a2 - T.mean(a2))
b1b2 = pm.Deterministic('b1b2', a1a2 - T.mean(a1a2))
mu = a0 + b1[x1] + b2[x2] + b1b2[x1, x2]
# define the likelihood
yl = pm.Normal('yl', mu=mu, tau=tau, observed=z)
# Generate a MCMC chain
start = pm.find_MAP()
steps = pm.Metropolis()
trace = pm.sample(20000, steps, start=start, progressbar=True)
# EXAMINE THE RESULTS
burnin = 2000
thin = 50
# Print summary for each trace
#pm.summary(trace[burnin::thin])
#pm.summary(trace)
# Check for mixing and autocorrelation
#pm.autocorrplot(trace[burnin::thin], vars=model.unobserved_RVs[:-1])
## Plot KDE and sampled values for each parameter.
pm.traceplot(trace[burnin::thin])
# Use PyMC3 to construct a model context
basic_model = pymc3.Model()
with basic_model:
# Define our prior belief about the fairness
# of the coin using a Beta distribution
theta = pymc3.Beta("theta", alpha=alpha, beta=beta)
# Define the Bernoulli likelihood function
y = pymc3.Binomial("y", n=n, p=theta, observed=z)
# Carry out the MCMC analysis using the Metropolis algorithm
# Use Maximum A Posteriori (MAP) optimisation as initial value for MCMC
start = pymc3.find_MAP()
# Use the Metropolis algorithm (as opposed to NUTS or HMC, etc.)
step = pymc3.Metropolis()
# Calculate the trace
trace = pymc3.sample(iterations,
step,
start,
random_seed=1,
progressbar=True)
# Plot the posterior histogram from MCMC analysis
bins = 50
plt.hist(trace["theta"],
bins,
histtype="step",
normed=True,
label="Posterior (MCMC)",
y = y + [1] * heads + [0] * (flips-heads)
coin = coin + [i] * flips
# Specify the model in PyMC
with pm.Model() as model:
# define the hyperparameters
mu = pm.Beta('mu', 2, 2)
kappa = pm.Gamma('kappa', 1, 0.1)
# define the prior
theta = pm.Beta('theta', mu * kappa, (1 - mu) * kappa, shape=len(N))
# define the likelihood
y = pm.Bernoulli('y', p=theta[coin], observed=y)
# Generate a MCMC chain
start = pm.find_MAP() # find a reasonable starting point.
step1 = pm.Metropolis([theta, mu])
step2 = pm.NUTS([kappa])
trace = pm.sample(10000, [step1, step2], start=start, random_seed=(123), progressbar=False)
## Check the results.
burnin = 2000 # posterior samples to discard
thin = 10 # posterior samples to discard
## Print summary for each trace
#pm.summary(trace[burnin::thin])
#pm.summary(trace)
## Check for mixing and autocorrelation
pm.autocorrplot(trace[burnin::thin], vars =[mu, kappa])
#pm.autocorrplot(trace, vars =[mu, kappa])
import pymc3 as pm
import numpy as np
import pandas as pd
x = np.array([1.1, 1.9, 2.3, 1.8])
model = pm.Model()
with model:
# priors
mu = pm.Normal('mu', mu=0, sd=100) # or tau=0.001 == 1/100**2
sigma = pm.Uniform('sigma', lower=.1, upper=10)
# data come from a Gaussian
x = pm.Normal('x', mu=mu, sd=sigma, observed=x)
# instantiate sampler
stepFunc = pm.Metropolis() # or try pm.NUTS()
# draw posterior samples (in 4 parallel running chains)
Nsample = 1000
Nchains = 4
traces = pm.sample(Nsample, step=stepFunc, njobs=Nchains)
plotVars = ('mu', 'sigma')
axs = pm.traceplot(traces, vars=plotVars, combined=False)
# plot joint posterior samples
tstr = 'Joint posterior samples'
post = np.vstack([traces['mu'], traces['sigma']])
post = post.transpose()
df = pd.DataFrame(post, columns=plotVars)
ax = df.plot(kind='scatter',
x=plotVars[0],
y=plotVars[1],
kappa1 = pm.Gamma('kappa1', alpha=shape_Gamma, beta=rate_Gamma, shape=n_cond)
a_Beta1 = mu[cond_of_subj] * kappa1[cond_of_subj]
b_Beta1 = (1 - mu[cond_of_subj]) * kappa1[cond_of_subj]
#Prior on theta
theta0 = pm.Beta('theta0', a_Beta0, b_Beta0, shape=n_subj)
theta1 = pm.Beta('theta1', a_Beta1, b_Beta1, shape=n_subj)
# if model_index == 0 then sample from theta1 else sample from theta0
theta = pm.switch(pm.eq(model_index, 0), theta1, theta0)
# Likelihood:
y = pm.Binomial('y', p=theta, n=n_trl_of_subj, observed=n_corr_of_subj)
# Sampling
step1 = pm.Metropolis([kappa0, kappa1, mu])
step2 = pm.NUTS([theta0, theta1])
step3 = pm.ElemwiseCategorical(vars=[model_index],values=[0,1])
trace = pm.sample(5000, step=[step1, step2, step3], progressbar=False)
# EXAMINE THE RESULTS.
burnin = 500
pm.traceplot(trace)
model_idx_sample = trace['model_index'][burnin:]
pM1 = sum(model_idx_sample == 1) / len(model_idx_sample)
pM2 = 1 - pM1
plt.figure(figsize=(15, 15))
G = pm.Normal('G',
mu=np.zeros(num_states - 1),
sd=np.ones(num_states - 1) * 10000.,
shape=(num_states - 1))
states = CommitmentProcess('states',
PI=PI,
Q=Q,
renewal_mask=renewal_mask,
num_states=num_states,
shape=(num_custs, obs_len),
testval=states_test_val)
usage = UsageProcess('usage',
alpha=A,
th0=th0,
G=G,
states=states,
num_states=num_states,
shape=(num_custs),
observed=observed_usage)
start = pm.find_MAP(method='Powell')
step1 = pm.Metropolis(vars=[r, PI, Q, A, G, th0, usage])
step2 = pm.CategoricalGibbsMetropolis(vars=[states])
trace = pm.sample(draws, start=start, step=[step1, step2], chains=chains)
print('saving to ' + args.output_dir)
pm.backends.ndarray.save_trace(trace,
directory=args.output_dir,
overwrite=True)
order_means_potential = pm.Potential(
'order_means_potential',
tt.switch(means[1] - means[0] < 0, -np.inf, 0) +
tt.switch(means[2] - means[1] < 0, -np.inf, 0))
# measurement error
sd = pm.Uniform('sd', lower=0, upper=20)
# latent cluster of each observation
category = pm.Categorical('category', p=p, shape=ndata)
# likelihood for each observed value
points = pm.Normal('obs', mu=means[category], sd=sd, observed=data)
with model:
step1 = pm.Metropolis(vars=[p, sd, means])
step2 = pm.ElemwiseCategorical(vars=[category], values=[0, 1, 2])
tr = pm.sample(10000, step=[step1, step2])
pm.plots.traceplot(tr, ['p', 'sd', 'means'])
pm.plots.traceplot(tr[5000::5], ['p', 'sd', 'means'])
#Sampling of cluster for individual data point
i = 0
plt.plot(tr['category'][5000::5, i], drawstyle='steps-mid')
plt.axis(ymin=-.1, ymax=2.1)
def cluster_posterior(i=0):
print('true cluster:', v[i])
print(' data value:', np.round(data[i], 2))
