dietr: an R package for calculating fractional trophic levels from quantitative and qualitative diet data

This article introduces an R package,dietr, which calculates fractional trophic levels from quantitative diet item and qualitative food item data following the routine implemented inTrophLabwithin the open source R environment.dietris easy to use and can quickly calculate trophic levels for many diet records. In addition to calculating trophic levels following theTrophLabroutines, users can also specify a taxonomic hierarchy and estimate trophic levels at multiple taxonomic levels in a single call of a function. Additionally,dietrworks well with FishBase data obtained in R usingrfishbaseand comes with pre-made databases of prey trophic levels that users can utilize for estimating trophic levels.dietrcan also calculate several prey electivity indices. I provide information ondietr's performance and provide a use case example of howdietrcan be used on an empirical dataset. Trophic levels for hundreds of specimens can be calculated in a few seconds and the flexibility ofdietr's input allows users to easily calculate trophic levels from their own data.