# Entropy calculation example

Pdf with task data (CZE)

The example of Entropy calculation

The example of Entropy calculation

$H(Vit(B)) = - \frac{n_{+}(Vitamin(B))}{Vitamin(B)} * log (\frac{n_{+}(Vitamin(B))}{Vitamin(B)})- \frac{n_{-}(Vitamin(B))}{Vitamin(B)} * log (\frac{n_{-}(Vitamin(B))}{Vitamin(B)}) $

where $n_{-}$ they died

where $n_{+}$ they survived

The formula for Entropy

The formula for Entropy

$H(A(v)) = - \sum_{t=1}^{T} \frac{n_{t}(A(v))} {n(A(v))}* log (\frac{n_{t}(A(v))} {n(A(v))}) $

where $n_t(A(v))$ is frequency of inputs which belongs to target class with value

**t**and also have value

**v**for attribute

**A**

where $n(A(v))$ is frequency of inputs which have value

**v**for attribute

**A**