task,program_id,role,outcome,failure,heldout_log_score,source dugongs,01-reference,Reference,scored,,-4.5586,"import numpy as np import pymc as pm def model(data): """"""Dugong length against age: the growth curve and priors of BoxingGym's dugongs environment, with a Normal likelihood and a fixed noise scale. """""" age = np.asarray(data[""age""], dtype=float) y = np.asarray(data[""length""], dtype=float) with pm.Model() as dugongs_model: age_data = pm.Data(""age_data"", age) alpha = pm.Normal(""alpha"", mu=2.0, sigma=0.2) beta = pm.Normal(""beta"", mu=1.5, sigma=0.5) lam = pm.Normal(""lam"", mu=0.4, sigma=0.5) mu = alpha - beta * pm.math.abs(lam) ** age_data pm.Normal(""length"", mu=mu, sigma=0.25, observed=y) return dugongs_model " dugongs,02-floor-model,Floor model,scored,,-14.0898,"import numpy as np import pymc as pm def model(data): """"""Floor model: ignores age and fits one mean length."""""" y = np.asarray(data[""length""], dtype=float) with pm.Model() as null_model: intercept = pm.Normal(""intercept"", mu=0.0, sigma=10.0) sigma = pm.HalfNormal(""sigma"", sigma=5.0) pm.Normal(""length"", mu=intercept, sigma=sigma, observed=y) return null_model " dugongs,03-single-attempt-1,Single attempt 1,scored,,-4.6292,"import pymc as pm import numpy as np def model(data): """""" Probabilistic model of dugong length as a function of age. Uses a von Bertalanffy growth model or similar asymptotic growth curve. The von Bertalanffy model is commonly used for animal growth: L(t) = L_inf * (1 - exp(-k * (t - t0))) Parameters: - L_inf: asymptotic maximum length - k: growth rate coefficient - t0: theoretical age at which length is zero (often negative) We place weakly informative priors on these parameters. """""" age = data[""age""] length = data[""length""] with pm.Model() as dugong_model: # Priors for von Bertalanffy parameters # L_inf: asymptotic length, must be positive. Based on data, max length is ~2.74 # So L_inf should be somewhat larger than that. L_inf = pm.HalfNormal(""L_inf"", sigma=2.0) # k: growth rate, positive k = pm.HalfNormal(""k"", sigma=1.0) # t0: theoretical age at zero length. Can be negative. # We use a Normal prior centered at a small negative value with reasonable spread t0 = pm.Normal(""t0"", mu=-0.5, sigma=0.5) # Deterministic growth curve mu = L_inf * (1 - pm.math.exp(-k * (age - t0))) # Ensure mu is positive (should be by construction if L_inf > 0 and k > 0) # Add likelihood sigma = pm.HalfNormal(""sigma"", sigma=0.2) length_obs = pm.Normal(""length_obs"", mu=mu, sigma=sigma, observed=length) return dugong_model " dugongs,04-single-attempt-2,Single attempt 2,scored,,-3.1969,"import pymc as pm import numpy as np def model(data): age = data['age'] length = data['length'] with pm.Model() as dugong_model: # Priors for the von Bertalanffy growth parameters # L_infinity: asymptotic length L_inf = pm.HalfNormal('L_inf', sigma=2) # k: growth rate k = pm.HalfNormal('k', sigma=1) # Observation noise sigma = pm.HalfNormal('sigma', sigma=0.2) # Expected length # Using the von Bertalanffy growth function: L(t) = L_inf * (1 - exp(-k * t)) mu = L_inf * (1 - pm.math.exp(-k * age)) # Likelihood likelihood = pm.Normal('likelihood', mu=mu, sigma=sigma, observed=length) return dugong_model " dugongs,05-single-attempt-3,Single attempt 3,scored,,-4.6876,"import pymc as pm import numpy as np def model(data): ages = data['age'] lengths = data['length'] with pm.Model() as model: # Priors for Von Bertalanffy parameters # L_inf: asymptotic length. Max observed is ~2.74. # A HalfNormal with sigma=2.0 allows reasonable mass above 2.74. L_inf = pm.HalfNormal('L_inf', sigma=2.0) # k: growth coefficient. Positive. k = pm.HalfNormal('k', sigma=1.0) # t0: theoretical age at length 0. Can be negative. t0 = pm.Normal('t0', mu=0.0, sigma=1.0) # Deterministic growth curve mu = L_inf * (1 - pm.math.exp(-k * (ages - t0))) # Observation noise sigma = pm.HalfNormal('sigma', sigma=0.2) # Likelihood length_obs = pm.Normal('length_obs', mu=mu, sigma=sigma, observed=lengths) return model " dugongs,06-single-attempt-4,Single attempt 4,scored,,-3.2267,"import pymc as pm import numpy as np def model(data): age = data['age'] length = data['length'] with pm.Model() as dugong_model: # Priors for the von Bertalanffy-like growth model: L = L_max * (1 - exp(-k * age)) # L_max: Asymptotic maximum length # k: Growth rate coefficient # Based on summary stats: # Max length is ~2.74, so L_max should be slightly higher. # We use a HalfNormal with a sigma large enough to cover plausible values. L_max = pm.HalfNormal('L_max', sigma=2.0) # k should be positive. A HalfNormal with sigma=1 is a reasonable weakly informative prior. k = pm.HalfNormal('k', sigma=1.0) # Deterministic growth curve mu = L_max * (1 - pm.math.exp(-k * age)) # Likelihood # sigma is the standard deviation of the observation error sigma = pm.HalfNormal('sigma', sigma=0.5) likelihood = pm.Normal('likelihood', mu=mu, sigma=sigma, observed=length) return dugong_model " dugongs,07-loop-proposal-1,Loop proposal 1 (round 1),scored,,-4.9166,"import pymc as pm import numpy as np def model(data): age = data['age'] length = data['length'] n_obs = len(age) with pm.Model() as model: # Create data container for age age_data = pm.Data('age', age, dims=""obs_id"") # Priors for von Bertalanffy growth parameters L_inf = pm.HalfNormal('L_inf', sigma=3.0) k = pm.HalfNormal('k', sigma=1.0) t0 = pm.Normal('t0', mu=0.0, sigma=1.0) # Expected length at each age mu = L_inf * (1 - pm.math.exp(-k * (age_data - t0))) # Likelihood sigma = pm.HalfNormal('sigma', sigma=0.5) y_obs = pm.Normal('y_obs', mu=mu, sigma=sigma, observed=length, dims=""obs_id"") return model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace" dugongs,08-loop-proposal-2,Loop proposal 2 (round 1),scored,,-4.6634,"import numpy as np import pymc as pm def model(data): """""" von Bertalanffy growth model for dugong length as a function of age. """""" age = data['age'] length = data['length'] with pm.Model() as dugong_model: # Data containers age_data = pm.Data(""age"", age, dims=""obs_id"") # Priors for von Bertalanffy parameters # L∞: asymptotic length, should be > max observed length L_inf = pm.HalfNormal(""L_inf"", sigma=3.0) # k: growth rate, positive k = pm.HalfNormal(""k"", sigma=2.0) # t0: theoretical age at zero length, can be negative t0 = pm.Normal(""t0"", mu=0.0, sigma=1.0) # Expected length mu = L_inf * (1 - pm.math.exp(-k * (age_data - t0))) # Observation model sigma = pm.HalfNormal(""sigma"", sigma=0.5) y_obs = pm.Normal(""y_obs"", mu=mu, sigma=sigma, observed=length, dims=""obs_id"") return dugong_model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace" dugongs,09-loop-proposal-3,Loop proposal 3 (round 2),scored,,-7.4306,"import pymc as pm import numpy as np def model(data): """""" Bayesian von Bertalanffy growth model with Log-Normal likelihood. This model addresses the critique that a simple Normal likelihood with constant variance may not capture the heteroscedasticity and skewness in dugong length data. By using a Log-Normal likelihood, we assume the errors are multiplicative, which is often more appropriate for biological growth data. """""" age = data['age'] length = data['length'] with pm.Model() as dugong_model: # Data container for age age_data = pm.Data('age', age, dims=""obs_id"") # Priors for von Bertalanffy growth parameters # L_inf: Asymptotic length. HalfNormal with sigma=3.0 allows for lengths up to ~6m (3 sigma), # which is biologically plausible for dugongs. L_inf = pm.HalfNormal('L_inf', sigma=3.0) # k: Growth rate coefficient. HalfNormal with sigma=2.0 is weakly informative. k = pm.HalfNormal('k', sigma=2.0) # t0: Theoretical age at zero length. Normal centered at 0 with sigma=1.0. # This allows for negative t0 (early growth) or positive t0 (delayed start). t0 = pm.Normal('t0', mu=0.0, sigma=1.0) # Expected length according to von Bertalanffy growth function vb_mean = L_inf * (1 - pm.math.exp(-k * (age_data - t0))) # Ensure vb_mean is positive to take log. # In practice, with reasonable priors and data, this should be positive. # We add a small epsilon for numerical stability if needed, but # the model should constrain it naturally. mu_log = pm.math.log(vb_mean) # Observation model: Log-Normal likelihood # sigma is the standard deviation on the log scale. sigma = pm.HalfNormal('sigma', sigma=0.5) # Observed likelihood y_obs = pm.LogNormal('y_obs', mu=mu_log, sigma=sigma, observed=length, dims=""obs_id"") return dugong_model def gen_model(observed_data): # Convert pandas DataFrame to dictionary of numpy arrays data_dict = {column: observed_data[column].to_numpy() for column in observed_data.columns} built_model = model(data_dict) with built_model: # Sample from posterior trace = pm.sample( 200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True} ) # Generate posterior predictive samples posterior_predictive = pm.sample_posterior_predictive( trace, random_seed=314, return_inferencedata=False ) return built_model, posterior_predictive, trace" dugongs,10-loop-proposal-4,Loop proposal 4 (round 2),scored,,-4.5121,"import pymc as pm import numpy as np def model(data): age = data['age'] length = data['length'] with pm.Model() as dugong_model: # Data containers age_data = pm.Data(""age"", age, dims=""obs_id"") # Priors for von Bertalanffy parameters L_inf = pm.HalfNormal(""L_inf"", sigma=3.0) k = pm.HalfNormal(""k"", sigma=2.0) t0 = pm.Normal(""t0"", mu=0.0, sigma=1.0) # Expected length mu = L_inf * (1 - pm.math.exp(-k * (age_data - t0))) # Heteroscedastic noise model: sigma scales with the mean length # alpha is the log-scale intercept, beta is the scaling factor alpha = pm.Normal(""alpha"", mu=0.0, sigma=1.0) beta = pm.Normal(""beta"", mu=0.0, sigma=0.5) sigma = pm.math.exp(alpha + beta * pm.math.log(mu)) # Likelihood y_obs = pm.Normal(""y_obs"", mu=mu, sigma=sigma, observed=length, dims=""obs_id"") return dugong_model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace" disease-spread,01-reference,Reference,scored,,-45.6085,"import pymc as pm def model(data): """"""Infected count against time: the exponential-approach curve and prior of BoxingGym's disease-spread environment, with a Binomial likelihood over a population of 50. """""" with pm.Model() as result: t = pm.Data(""t"", data[""Time""]) y = pm.Data(""y"", data[""Infected_Count""]) theta = pm.TruncatedNormal(""theta"", mu=1, sigma=1, lower=0, upper=2) pm.Binomial(""Infected_Count"", n=50, p=1-pm.math.exp(-theta*t), observed=y) return result " disease-spread,02-floor-model,Floor model,scored,,-262.1291,"import pymc as pm def model(data): """"""Floor model: ignores time and fits one infection probability."""""" with pm.Model() as result: y = pm.Data(""y"", data[""Infected_Count""]) p = pm.Beta(""p"", alpha=1, beta=1) pm.Binomial(""Infected_Count"", n=50, p=p, observed=y) return result " disease-spread,03-single-attempt-1,Single attempt 1,scored,,-59.9733,"import pymc as pm import numpy as np def model(data): """""" Construct a PyMC model for the death_process task. Parameters: data (dict): A dictionary containing 'Time' and 'Infected_Count' arrays. Returns: pm.Model: The PyMC model. """""" times = np.array(data['Time']) infected_counts = np.array(data['Infected_Count']) N = 50 # Total population size with pm.Model() as pmodel: # Define parameters for the model # We assume a linear relationship between time and the logit of the probability of infection # p(t) = sigmoid(alpha + beta * t) # Then the number of infected follows a Binomial(N, p(t)) # Priors for the linear coefficients alpha = pm.Normal('alpha', mu=0, sigma=10) beta = pm.Normal('beta', mu=0, sigma=10) # Calculate the probability of infection at each time point logit_p = alpha + beta * times p = pm.math.sigmoid(logit_p) # Observed likelihood infected_observed = pm.Binomial('infected_observed', n=N, p=p, observed=infected_counts) return pmodel " disease-spread,04-single-attempt-2,Single attempt 2,scored,,-59.8279,"import pymc as pm import numpy as np def model(data): """""" Defines a PyMC model for predicting infected counts in a population of 50. Args: data (dict): A dictionary containing 'Time' and 'Infected_Count' arrays. Returns: pm.Model: The defined PyMC model. """""" time = np.array(data['Time']) infected_counts = np.array(data['Infected_Count']) N = 50 # Total population size with pm.Model() as m: # Priors for the logistic regression coefficients # alpha: intercept, beta: slope alpha = pm.Normal('alpha', mu=0, sigma=5) beta = pm.Normal('beta', mu=0, sigma=5) # Compute the probability of infection at each time point # Using the logistic function: p = 1 / (1 + exp(-(alpha + beta * t))) logit_p = alpha + beta * time p = pm.math.invlogit(logit_p) # Observed likelihood: Binomial distribution # The number of infected individuals is binomially distributed with N trials and probability p infected_observed = pm.Binomial( 'infected_observed', n=N, p=p, observed=infected_counts ) return m " disease-spread,05-single-attempt-3,Single attempt 3,scored,,-60.0128,"import pymc as pm import numpy as np def model(data): time = np.array(data['Time']) infected_counts = np.array(data['Infected_Count']) with pm.Model() as model: # Priors for the logistic curve parameters # beta: growth rate, should be positive beta = pm.Gamma('beta', alpha=2, beta=1) # t_mid: midpoint of the logistic curve, centered around 1.0 based on data t_mid = pm.Normal('t_mid', mu=1.0, sigma=0.5) # Total population is fixed at 50 K = 50 # Deterministic logistic function # I(t) = K / (1 + exp(-beta * (t - t_mid))) expected_infected = pm.Deterministic( 'expected_infected', K / (1 + pm.math.exp(-beta * (time - t_mid))) ) # Likelihood # Using Gaussian likelihood for simplicity, as counts are relatively high # and the Gaussian approximation to Binomial is reasonable. # Alternatively, Binomial likelihood: Binomial(n=50, p=expected_infected/50) # Let's use Binomial for better statistical grounding. p_infected = expected_infected / K # Clip p to [0, 1] to avoid numerical issues p_infected = pm.math.clip(p_infected, 0, 1) likelihood = pm.Binomial( 'likelihood', n=50, p=p_infected, observed=infected_counts ) return model " disease-spread,06-single-attempt-4,Single attempt 4,failed,failed at model build,,"import numpy as np import pymc as pm import theano.tensor as tt def model(data): """""" Build a PyMC model for the death_process / infection spread problem. The data consists of Time and Infected_Count observations from a population of 50. We need to model the number of infected individuals as a function of time. A common model for disease spread is the logistic growth model (SIR-like), where: I(t) = N / (1 + ((N - I0) / I0) * exp(-r * t)) However, since we're observing noisy counts at specific times, we can use a simpler parametric model or a stochastic process model. Given the summary statistics: - Time ranges from ~0 to ~2 - Infected_Count ranges from 1 to 47 - Mean infected count is ~30 Let's use a logistic growth model with parameters: - r: growth rate - I0: initial infected count The logistic function: I(t) = N / (1 + ((N - I0) / I0) * exp(-r * t)) We'll place priors on r and I0, and use a likelihood that accounts for the discrete nature of the counts (e.g., Normal or Poisson approximation, or just Normal for simplicity since counts are relatively large). """""" N = 50 # Total population times = data['Time'] infected_counts = data['Infected_Count'] with pm.Model() as pm_model: # Priors on parameters # Growth rate r: positive, reasonable range r = pm.HalfNormal('r', sigma=5) # Initial infected count I0: between 1 and N # Using a Beta distribution scaled to [1, N] # Or directly use a discrete uniform or normal truncated I0 = pm.Beta('I0', alpha=2, beta=5, transform=pm.distributions.transforms.ordered) # Scale I0 to be between 1 and N-1 I0_scaled = I0 * (N - 2) + 1 # Deterministic: predicted infected count at each time point # Logistic growth: I(t) = N / (1 + ((N - I0) / I0) * exp(-r * t)) # Handle edge cases where I0 is very small # Using a safer formulation # Let's use a different parameterization to avoid numerical issues # I(t) = N * sigmoid(r * (t - t0)) # where t0 is the inflection point # sigmoid(x) = 1 / (1 + exp(-x)) # Alternative: use r and K (carrying capacity, which is N) # I(t) = N / (1 + exp(-r * (t - t_mid))) # where t_mid is the time at which I(t) = N/2 t_mid = pm.Normal('t_mid', mu=1.0, sigma=0.5) # Predicted infected count using logistic function I_pred = N / (1 + tt.exp(-r * (times - t_mid))) # Likelihood: observed counts are approximately normal around the predicted values # with some noise. Since counts are integers, we could use a Poisson or Negative Binomial, # but for simplicity and given the moderate counts, a Normal likelihood with a small # standard deviation works well. sigma = pm.HalfNormal('sigma', sigma=5) # Observed likelihood infected_obs = pm.Normal('infected_obs', mu=I_pred, sigma=sigma, observed=infected_counts) return pm_model " disease-spread,07-loop-proposal-1,Loop proposal 1 (round 1),scored,,-59.9324,"import numpy as np import pymc as pm def model(data): """""" Logistic growth model for disease spread. Assumptions: - Disease spread follows logistic growth - Total population is 50 (carrying capacity) - Observed counts follow a Binomial distribution - Priors are weakly informative to allow flexibility """""" # Extract data time = data['Time'] infected = data['Infected_Count'] N = 50 # Total population # Create PyMC model with pm.Model() as model: # Define feature container for time time_data = pm.Data('Time', time, dims='obs_id') # Priors for logistic growth parameters # r: growth rate (positive) # t0: inflection point (centered around 1, since that's where we see ~25 infected) r = pm.HalfNormal('r', sigma=5) t0 = pm.Normal('t0', mu=1.0, sigma=0.5) # Logistic function: I(t) = N / (1 + exp(-r*(t - t0))) # Compute the expected number of infected expected_infected = N / (1 + pm.math.exp(-r * (time_data - t0))) # Convert to probability for Binomial distribution p = expected_infected / N # Clip to avoid numerical issues p = pm.math.minimum(pm.math.maximum(p, 1e-10), 1 - 1e-10) # Observed likelihood - Binomial y_obs = pm.Binomial('y_obs', n=N, p=p, observed=infected, dims='obs_id') return model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace" disease-spread,08-loop-proposal-2,Loop proposal 2 (round 1),failed,failed at model build,,"import numpy as np import pymc as pm def model(data): time = data['Time'] infected = data['Infected_Count'] N = 50 # total population with pm.Model() as model: # Feature container for time time_data = pm.Data('Time', time, dims='obs_id') # Logistic growth parameters r = pm.HalfNormal('r', sigma=5) t0 = pm.Normal('t0', mu=1.0, sigma=0.5) # Deterministic logistic curve mu_infected = pm.Deterministic( 'mu_infected', N / (1 + pm.math.exp(-r * (time_data - t0))), dims='obs_id' ) # Overdispersion parameter sigma = pm.HalfNormal('sigma', sigma=5) # Negative Binomial likelihood y_obs = pm.NegativeBinomial( 'y_obs', mu=mu_infected, sigma=sigma, observed=infected, dims='obs_id' ) return model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace" disease-spread,09-loop-proposal-3,Loop proposal 3 (round 2),scored,,-60.5719,"import numpy as np import pymc as pm import pandas as pd def model(data): """""" Logistic growth model for disease spread with Negative Binomial likelihood. Assumptions: - Disease spread follows logistic growth dynamics. - Total population is fixed at 50. - Observed counts are subject to overdispersion relative to the logistic mean. - Negative Binomial likelihood is used to model the count data, allowing for extra variance beyond the Binomial constraint. """""" # Extract data time = data['Time'] infected = data['Infected_Count'] N = 50 # Total population # Create PyMC model with pm.Model() as model: # Define feature container for time time_data = pm.Data('Time', time, dims='obs_id') # Priors for logistic growth parameters # r: growth rate (positive). HalfNormal with sigma=5 allows for rapid growth. r = pm.HalfNormal('r', sigma=5) # t0: inflection point. Centered at 1.0 with reasonable uncertainty. t0 = pm.Normal('t0', mu=1.0, sigma=0.5) # Logistic function: I(t) = N / (1 + exp(-r*(t - t0))) # Compute the expected number of infected expected_infected = N / (1 + pm.math.exp(-r * (time_data - t0))) # Clip expected infected to ensure it stays within valid range for probability calculation # though NegativeBinomial takes mu directly, we might want to ensure positivity. # The logistic function naturally stays between 0 and N. # Overdispersion parameter for Negative Binomial # alpha is the dispersion parameter. Smaller alpha means more dispersion. # Using a HalfNormal prior for alpha. alpha = pm.HalfNormal('alpha', sigma=5) # Observed likelihood: Negative Binomial # pm.NegativeBinomial('y_obs', mu=expected_infected, alpha=alpha, observed=infected, dims='obs_id') # Note: In some PyMC versions, the parameterization might differ. # Standard parameterization is mu (mean) and alpha (dispersion). # Variance = mu + mu^2 / alpha y_obs = pm.NegativeBinomial('y_obs', mu=expected_infected, alpha=alpha, observed=infected, dims='obs_id') return model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace" disease-spread,10-loop-proposal-4,Loop proposal 4 (round 2),scored,,-60.7518,"import numpy as np import pymc as pm import pandas as pd def model(data): """""" Logistic growth model for disease spread with Negative Binomial likelihood. Assumptions: - Disease spread follows a logistic growth mean trend. - Total population is 50 (carrying capacity). - Observed counts exhibit overdispersion relative to Binomial, modeled via Negative Binomial. - Priors are weakly informative. """""" # Extract data time = data['Time'] infected = data['Infected_Count'] N = 50 # Total population # Create PyMC model with pm.Model() as model: # Define feature container for time time_data = pm.Data('Time', time, dims='obs_id') # Priors for logistic growth parameters # r: growth rate (positive, steep rise observed) r = pm.HalfNormal('r', sigma=10) # t0: inflection point (centered around 1.0, sigma=1.0 to be flexible) t0 = pm.Normal('t0', mu=1.0, sigma=1.0) # Logistic function: I(t) = N / (1 + exp(-r*(t - t0))) # Compute the expected number of infected expected_infected = N / (1 + pm.math.exp(-r * (time_data - t0))) # Clip expected infected to be within [1, N-1] to avoid log issues or zero/negative means # We want mean > 0 for NegativeBinomial. # Also, NegativeBinomial parametrization in PyMC uses mu and alpha (or n, p). # Using mu and alpha parametrization: mu is mean, alpha is dispersion. # Var = mu + mu^2 / alpha # Clip mean to be strictly positive and <= N mu = pm.math.minimum(pm.math.maximum(expected_infected, 0.5), N - 0.5) # Dispersion parameter for Negative Binomial # High alpha means low dispersion (closer to Poisson/Binomial) # Low alpha means high dispersion alpha = pm.HalfNormal('alpha', sigma=5) # Observed likelihood - Negative Binomial # mu is the mean, alpha is the dispersion parameter y_obs = pm.NegativeBinomial('y_obs', mu=mu, alpha=alpha, observed=infected, dims='obs_id') return model def gen_model(observed_data): built_model = model({column: observed_data[column].to_numpy() for column in observed_data.columns}) with built_model: trace = pm.sample(200, tune=200, target_accept=0.90, chains=1, cores=1, random_seed=42, idata_kwargs={""log_likelihood"": True}) posterior_predictive = pm.sample_posterior_predictive(trace, random_seed=314, return_inferencedata=False) return built_model, posterior_predictive, trace"