Ecological electivity and forage indices
A compact scientific package for calculating electivity and forage preference indices including Ivlev E, Jacobs D, and Vanderploeg and Scavia E*.
Designed to work seamlessly with Pandas dataframes.
pip install electivity
Every electivity function takes two parameters—a list of available resources and a list of consumed resources—and returns an equal-length Pandas Series of electivity values calculated element-wise. The easiest way to work with electivity is using Pandas dataframes, but any list-like data input will work. If a list output is desired, the output can be cast using list( ... ).
import pandas as pd
import electivity
# Build a dataframe of resource data
data = pd.DataFrame({"available": [10, 10, 10], "consumed": [10, 3, 0]})
# Calculate Ivlev electivity and assign it to a new column
data = data.assign(E=electivity.ivlev_electivity(data.available, data.consumed))| Function | Algorithm |
|---|---|
| ivlev_forage_ratio | Ivlev Forage Ratio E' (Ivlev 1961) |
| ivlev_electivity | Ivlev Electivity E (Ivlev 1961) |
| jacobs_electivity | Jacobs' Electivity D (Jacobs 1974) |
| jacobs_forage_ratio | Jacobs' Forage Ratio Q (Jacobs 1974) |
| strauss_linear | Strauss' Linear Index L (Strauss 1979) |
| chessons_alpha | Chesson's Alpha α (Chesson 1978) |
| relativized_electivity | Relativized Electivity Index E* (Vanderploeg & Scavia, 1979) |
Zuspan, A. 2021. electivity: Ecological electivity and forage indices, v2.0.0, Zenodo, doi:10.5281/zenodo.4567591
- Chesson, J. 1978. Measuring preference in selective predation. Ecology 59:211-215.
- Ivlev, V. S. 1961. Experimental ecology of the feeding of fishes. Yale Univ. Press, New Haven.
- Jacobs, J. 1974. Quantitative measurement of food selection. Oecologia (Berl) 14:413-417.
- Strauss, R. E. 1979. Reliability estimates for Ivlev's electivity index, the forage ratio, and a proposed linear index of food selection. Trans Am Fish Soc 108: 344-352.
- Vanderploeg H. A. and Scavia D. 1979. Calculation and use of selectivity coefficients of feeding: zooplankton grazing. Ecol Modelling 7:135-149.