sufficientStatistics.CatDirichlet {bbricks} R Documentation

## Sufficient statistics of a "CatDirichlet" object

### Description

For following Categorical-Dirichlet model structure:

pi|alpha \sim Dir(alpha)

x|pi \sim Categorical(pi)

Where Dir() is the Dirichlet distribution, Categorical() is the Categorical distribution. See `?dDir` and `dCategorical` for the definitions of these distribution.
The sufficient statistics of a set of samples x is:

• the effective counts of each unique label in x. i.e. T(x)[i] = sum(uniqueLabels[i]

### Usage

```## S3 method for class 'CatDirichlet'
sufficientStatistics(obj, x, foreach = FALSE, ...)
```

### Arguments

 `obj` A "CatDirichlet" object. `x` numeric,integer or character, samples of the Categorical distribution. `foreach` logical, specifying whether to return the sufficient statistics for each observation. Default FALSE. `...` Additional arguments to be passed to other inherited types.

### Value

An object of class "ssCat", the sufficient statistics of a set of categorical samples. Or an object of the same class as x if foreach=TRUE.

### References

Murphy, Kevin P. Machine learning: a probabilistic perspective. MIT press, 2012.

`CatDirichlet`, `sufficientStatistics_Weighted.CatDirichlet`

### Examples

```obj <- CatDirichlet(gamma=list(alpha=runif(26,1,2),uniqueLabels = letters))
x <- sample(letters,size = 20,replace = TRUE)
w <- runif(20)
sufficientStatistics(obj=obj,x=x)       #return the counts of each unique label
sufficientStatistics_Weighted(obj=obj,x=x,w=w) #return the weighted counts of each unique lable
sufficientStatistics(obj=obj,x=x,foreach = TRUE) #return the sample itself
```

[Package bbricks version 0.1.4 Index]