Utility to create an efficient quadtree spatial index of EPA-regulated facility locations

Index US EPA Facility Registry Service facility locations so getfrsnearby() can find them very quickly

Usage

indexfrs(frspts = NULL, indexname = "frs_index", envir = globalenv())

Arguments

frspts

optional, default is the frs table from the EJAM package, but could be a subset of that data.table with columns name lat and lon, one row per location (point), and any other columns are ignored. If frspts not specified and indexname exists already, just returns that index without rebuilding it. If frspts is specified, such as just frs from one industry or one state, then new index is built, even if one named indexname already existed.

envir

optional environment - default is to assign index object to globalenv()

Value

Index is returned and the side effect is it puts in the globalenv() (or specified envir) that spatial index with name defined by indexname, as created by indexpoints().

Details

This creates a quadtree spatial index of some or all facilities, to be used by getfrsnearby(), such as to count the regulated facilities near some other specified sites, or to create a new proximity score for every block and block group in the US, via proxistat()