Calculate Shannon entropy, following Tastle and Wierman.
Usage
entropy(V)
Arguments
V
A frequency vector
Value
The function returns the Shannon entropy.
Details
This function calculates the Shannon entropy following Tastle and Wierman (2007). A frequency vector describes the number of observations in a given category. For example, the vector [10,20,30,15,4] describes 10 observations with position 1, 20 observations with position 2, 30 observations with position 3, 15 observations with position 4, and 4 observations with position 5.
This function follows Tastle and Wierman and ignores categories with zero observations. This does not follow the formula indicated.
See consensus for a function that considers the order of categories.
References
Tastle, W., and M. Wierman. 2007. Consensus and dissention: A measure of ordinal dispersion. International Journal of Approximate Reasoning 45 (3): 531-545.