getPolygonID {MazamaSpatialUtils}

Get polygonID from SFDF of interest

Description

Extracts the the vector of unique polygon identifiers from SFDF.

This function is useful when writing code to aggregate data by polygon and calculate per-polygon statistics. Each unique simple features data frame will have a different set of data columns but each is guaranteed to have a column named polygonID that uniquely identifies each polygon.

This allows us to write code that aggregates by polygon without having to know whether the polygons represent, countries, timezones or HUCs, etc.

Usage

getPolygonID(SFDF)

Arguments

SFDF

Spatial polygons dataset of interest.

Value

Vector of polygon identifiers.