The Shannon evenness index, abbreviated as SEI, provides information on area composition and richness. It covers the number of different land cover types (m) observed along the straight line and their relative abundances (Pi). It is calculated by dividing the Shannon diversity index by its maximum (h (m)). Therefore it varies between 0 and 1 and is relatively easy to interpret.
m
SEI = SDI / max (SDI) = - ∑ (Pi * In (Pi)) / ln(m)
i