Package index • hercgeos

Example data sets

Small collections of, for example, shapefiles that are useful for testing or demonstrating the features of the package.

NASHVILLE_NH: Two 2020 Census tracts from the northern part of Nashua, NH.

UNIT_PENTAGON: An sfc object that is a five-sided polygon with area 1.

Metadata

Descriptions of the layout of data from TIGER/Line or other sources, as well as various defaults, like colors for maps of terrain.

DECENNIAL_POPULATION_VARIABLE_FORMATS: Formats for decennial census variables of overall population.

DECENNIAL_TABULATION_CROSSWALK: The layout for a crosswalk of tabulation blocks between decennial censuses

TERRAIN_COLORS: A named character vector of hex-encoded colors for water, developed and undeveloped land.

TIGER_ATTRIBUTES: A named character vector of shapefile attributes for data from TIGER/Line

Terrain

Categorize or display terrain, e.g. urban vs. rural, land vs. water

geom_terrain(): Plot census blocks by water or land use

is_water(): Identify geographies that are all water

terrain_factor(): Create a factor of terrains based on census reporting of water area and land use.

TIGER/Line functions

Read shapefiles that have been downloaded from the US Census Bureau’s TIGER/Line shapefile database.

fix_latlong_to_numeric(): Convert interpreted latitude and longitude from text to numbers

fix_names_by_coalescing(): Coalesce NAME and NAMELSAD fields to fix blank NAME entries

fix_old_geoids(): Replace ID fields with "GEOID"

fix_old_year_suffixes(): Remove year numbers from the end of field names

geoid_to_tract_id(): Extract the 4- or 6-digit tract codes from full census GEOID values

batch_read_tigershapes(): Load geographies from many shapefiles into a tibble of simple features

read_tigershapes(): Import data from US Census TIGER/Line shapefiles

transform_tiger_to_utm(): Transform native TIGER/Line lat-long features to UTM features

tiger_name_for(): Create a tigershape filename based upon state, year, and geography

Decennial census functions

A major use-case for this package is to map American Community Survey data from tracts to more concrete, real-world geographical places. One way to do this is to use block populations from each decennial census.

decennial_pl_variable(): Variable names for PL tables, per the idiosyncrasies of decennial censuses

truncate_decennial_tract_codes(): Lop off trailing "00"s from census tract codes from 2000.

crosswalk_spec(): Compute the names of the columns in a tabulation crosswalk table

read_crosswalk(): Read a file with crosswalk information between the blocks of two consecutive decennial censuses.

Geometric operations

Specialized functions that generally build upon more modularly-designed functions from the simple features package.

geometry_filter(): Filter one or more geometries by a reference geometry using a single geometric predicate.

central_utm(): Find the median UTM Zone from a vector of longitudes.

utm_crs(): Create a coordinate reference system for a UTM Zone and datum.

utm_zone_from_longitude(): Identify the UTM Zone that corresponds to a longitude