tests/testthat/helpers/predictor_handlers.R

In projpred: Projection Predictive Feature Selection

# Expand poly() terms, e.g., `poly(x, 2, raw = TRUE)` to
# `poly(x, 2, raw = TRUE)1` and `poly(x, 2, raw = TRUE)2`:
expand_poly <- function(trms, info_str) {
  poly_trms <- grep("poly[m]*\\(.*\\)", trms, value = TRUE)
  if (length(poly_trms)) {
    poly_degree <- sub(
      "poly[m]*\\(.*,.*([[:digit:]]+).*", "\\1",
      poly_trms
    )
    poly_degree <- unique(poly_degree)
    if (length(poly_degree) != 1) {
      stop("This test needs to be adapted. Info: ", info_str)
    }
    poly_degree <- as.integer(poly_degree)
    trms <- c(
      setdiff(trms, poly_trms),
      unlist(lapply(poly_trms, function(poly_trms_i) {
        paste0(poly_trms_i, seq_len(poly_degree))
      }))
    )
  }
  return(trms)
}