Compositional functional isotemporal substitution analysis (CFISA)

The proposed method CFISA is performed to assess how varying the weight of a specific range of density influences response variable.

Requirements

Calculations were performed in following software, using these libraries:

• R version: 4.2.1 (2022-06-23) -- "Funny-Looking Kid"
• Libraries:
  • robCompositions: log-ratio transformations; version 2.4.1
  • fda: statistical analyses of functions; version 6.1.4
  • car: logit transformation; version 3.1-2

Available scripts

1. function.R:
   a) clr2density - back transformation from L^2 to B^2

   b) ZsplineBasis - basis with zero integral

   c)SmoothingSpline01 - smoothing spline

   All these functions was introduced in "Talská, R., Hron, K. & Grygar, T.M. Compositional Scalar-on-Function Regression with Application to Sediment Particle Size Distributions. Math Geosci 53, 1667–1695 (2021). https://doi.org/10.1007/s11004-021-09941-1"

   d)bpc1 - backwards pivot coordinates

   e) is - main function to calculate isotemporal substitution

2. CFISA.R