Build an h3t tile SQL query for an OBIS biodiversity indicator

Generates the read-only SELECT (projecting exactly cell_id, value, n) that the h3t service base64-decodes, validates, and executes per tile. {{res}} is substituted server-side with the tile's H3 resolution.

Usage

obis_h3t_sql(
  indicator = c("es", "sp", "shannon", "n"),
  taxon = NULL,
  years = NULL,
  esn = 50L,
  res_max = 7L,
  res_placeholder = "{{res}}"
)

Arguments

indicator

one of "es" (ES50), "sp" (richness), "shannon", "n" (# records).

taxon

optional named list/vector restricting taxa, names among phylum, class, order, family, genus, species, e.g. list(class = "Aves") or list(phylum = c("Mollusca", "Cnidaria")).

years

optional c(min, max) year range (either may be NA).

esn

expected sample size for ES(n); default 50.

res_max

cap on the H3 resolution (1-7). Lower = coarser/bigger hexagons at a given map zoom (the "base zoom level" control); the store's finest resolution is 7. Default 7 (track zoom up to the finest).

res_placeholder

the resolution placeholder; default "{{res}}".

Value

a single-line-friendly SQL string.

Details

With no taxon/years filter the query reads the precomputed idx_h3 layer (fast). With a filter it computes the indicator on the fly from the species-level occ_h3 store, selecting the resolution tier that matches the tile zoom.