curvr: curvr: Calculate Point-Wise Curvature From Landmarked...
In mannfred/curvr: Calculate Total Curvature From Landmarked Specimens

curvr

R Documentation

curvr: Calculate Point-Wise Curvature From Landmarked Specimens

Description

Calculate point-wise curvature from landmarked specimens that have been fitted by polynomials in Momocs. Polynomials are parameterized by arc length to ensure even sampling intervals across the curve. Point-wise curvature is summed across the polynomial, outputting 'total curvature'.

curvr functions

The main function of curvr is total_curvature() - it calculates point-wise curvature along bounded polynomials fitted to curved specimens (e.g. corolla tubes, bird bills).

Calculating point-wise curvature, K, involves parameterizing the fitted polynomial function by arclength and computing the tangent directions along the curve. The helper function parameterize() converts polynomial objects from Momocs into t-parameterized polynomials readable by pracma::arclength(). as_function() computes the y coordinates of our polynomial once the x-coordinates of the arclength-parameterized function are known. as_expression() converts a Momocs polynomial to an expression so that derivatives can be computed using stats::deriv3().