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Gini-Simpson Index

Source: R/inequ.R
concstats_simpson.Rd

Gini-Simpson Index

Usage

concstats_simpson(x, na.rm = TRUE)

Arguments

x

A non-negative numeric vector.

na.rm

A logical vector that indicates whether NA values should be excluded or not. Must be either TRUE or FALSE. The default is TRUE. If set to FALSE the computation yields NA if NA values are present.

Value

A single numeric value in decimal form.

Details

concstats_simpson is the Gini-Simpson index, also known as the Gini impurity (Gini's diversity index) in Machine Learning, Gibbs-Martin index or Blau index in sociology and management studies. This index ranges from (0, 1).

References

Simpson, E. H. (1949). "Measurement of Diversity", Nature, 163, 688.

Jost, L. (2006). "Entropy and Diversity". Oikos, 113(2), 363-375.

Examples

# a vector of market shares
x <- c(0.4, 0.2, 0.25, 0.1, 0.05)
concstats_simpson(x)
#> [1] 0.81875
# a vector with NA values
x <- c(0.4, 0.2, 0.25, 0.1, 0.05, NA)
concstats_simpson(x, na.rm = FALSE)
#> [1] NA