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DOI

electivity

Ecological electivity and forage indices

Description

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.

Installation

pip install electivity

Usage

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( ... ).

Example

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))

Functions and indices

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)

Citation

Zuspan, A. 2021. electivity: Ecological electivity and forage indices, v2.0.0, Zenodo, doi:10.5281/zenodo.4567591

References

  • 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.