Size class of each fish from a table of length breaks

Each break row covers [length_min_mm, length_max_mm) for one species group, so a fish exactly on a break takes the upper class. The breaks must tile every group that has a measured fish: a fish with a positive length that falls in no class, or in more than one, is an error rather than an NA, because a gap or an overlap in the table would otherwise read as "unmeasured".

Usage

knw_size_class(species_group, length_mm, breaks)

Arguments

species_group

character species group per fish, matched against breaks$species_group.

length_mm

numeric length per fish, same length as species_group. NA, zero and negative lengths are unmeasured and return NA.

breaks

data.frame with columns species_group, size_class, length_min_mm and length_max_mm (use Inf for an open top class).

Value

character size class per fish, NA where unmeasured.

Examples

breaks <- data.frame(
  species_group = c("CH", "CH"),
  size_class    = c("fry", "parr"),
  length_min_mm = c(0, 70),
  length_max_mm = c(70, Inf)
)
knw_size_class(c("CH", "CH", "CH"), c(45, 70, NA), breaks)
#> [1] "fry"  "parr" NA