## README ¶

### Infergo — Go programs that learn

`infergo` is a probabilistic programming facility for the Go language. `infergo` allows to write probabilistic models in almost unrestricted Go and relies on automatic differentiation for optimization and inference.

#### Example

Learning parameters of the Normal distribution from observations.

##### Model
``````type Model struct {
Data []float64
}

// x is the mean, x is the log stddev of the distribution
func (m *Model) Observe(x []float64) float64 {
// Our prior is a unit normal ...
ll := Normal.Logps(0, 1, x...)
// ... but the posterior is based on data observations.
ll += Normal.Logps(x, math.Exp(x), m.Data...)
return ll
}
``````
##### Inference
``````// Data
m := &Model{[]float64{
-0.854, 1.067, -1.220, 0.818, -0.749,
0.805, 1.443, 1.069, 1.426, 0.308}}

// Parameters
mean, logs := 0., 0.
x := []float64{mean, logs}

// Optimiziation
opt := &infer.Momentum{
Rate:  0.01,
Decay: 0.998,
}
for iter := 0; iter != 1000; iter++ {
opt.Step(m, x)
}
mean, logs := x, x

// Posterior
hmc := &infer.HMC{
L:   10,
Eps: 0.1,
}
samples := make(chan []float64)
hmc.Sample(m, x, samples)
for i := 0; i != 1000; i++ {
x = <-samples
}
hmc.Stop()
``````

#### Acknowledgements

I owe a debt of gratitude to Frank Wood who introduced me to probabilistic programming and inspired me to pursue probabilistic programming paradigms and applications. I also want to thank Jan-Willem van de Meent, with whom I had fruitful discussions of motives, ideas, and implementation choices behind `infergo`, and whose thoughts and recommendations significantly influenced `infergo` design. Finally, I want to thank PUB+, the company I work for, for supporting me in development of `infergo` and letting me experiment with applying probabilistic programming to critical decision-making in production environment.

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## Directories ¶

Path Synopsis
Package ad implements automatic differentiation of a model.
Package ad implements automatic differentiation of a model.
cmd
Package dist provides differentiatable distribution models.
Package dist provides differentiatable distribution models.
examples
Gaussian mixture
Gaussian mixture
Inferring parameters of the Normal distribution from observations
Inferring parameters of the Normal distribution from observations
Inferring parameters of the Normal distribution from observations
Inferring parameters of the Normal distribution from observations
Determining the best bandwidth for page-per-visit prediction (http://dtolpin.github.io/posts/session-depth/)
Determining the best bandwidth for page-per-visit prediction (http://dtolpin.github.io/posts/session-depth/)
The eight schools example as appears in PyStan documentation (and taken from "Bayesian Data Analysis", Section 5.5 by Gelman et al.i): data { int<lower=0> J; // number of schools vector[J] y; // estimated treatment effects vector<lower=0>[J] sigma; // s.e.
The eight schools example as appears in PyStan documentation (and taken from "Bayesian Data Analysis", Section 5.5 by Gelman et al.i): data { int<lower=0> J; // number of schools vector[J] y; // estimated treatment effects vector<lower=0>[J] sigma; // s.e.
Package infer contains inference algorithms: maximum likelihood estimation by gradient descent and approximation of the posterior by Markov Chain Monte Carlo methods (notably Hamiltonian Monte Carlo family of algorithms).
Package infer contains inference algorithms: maximum likelihood estimation by gradient descent and approximation of the posterior by Markov Chain Monte Carlo methods (notably Hamiltonian Monte Carlo family of algorithms).
Package mathx provides auxiliary elemental functions, ubiquitously useful but not found in package math.
Package mathx provides auxiliary elemental functions, ubiquitously useful but not found in package math.
Package model specifies the interface of a probabilistc model.
Package model specifies the interface of a probabilistc model.