This is the core function within the package for areal weighted interpolation. It validates both data sources before interpolating one or more listed values from the source data into the target data.
aw_interpolate(.data, tid, source, sid, weight = "sum", output = "sf", extensive,
intensive)A sf object that data should be interpolated to (this is referred
to as the target elsewhere in the package).
A unique identification number within target
A sf object with data to be interpolated
A unique identification number within source
For "extensive" interpolations, should be either "total" or
"sum". For "intensive" interpolations, should be "sum". For mixed
interpolations, this will only impact the calculation of the extensive variables.
One of either "sf" or "tibble"
A vector of quoted variable names to be treated as spatially extensive
(e.g. population counts); optional if intensive is specified
A vector of quoted variable names to be treated as spatially intensive
(e.g. population density); optional if extensive is specified
A sf object or a tibble with the value or values interpolated into
the target data.
Areal weighted interpolation can be used for generating demographic estimates for overlapping but incongruent polygon features. It assumes that individual members of a population are evenly dispersed within the source features (an assumption not likely to hold in the real world). It also functions best when data are in a projected coordinate system, like the UTM coordinate system.
aw_interpolate(ar_stl_wards, tid = WARD, source = ar_stl_race, sid = GEOID, weight = "sum",
output = "sf", extensive = "TOTAL_E")
#> Simple feature collection with 28 features and 4 fields
#> Geometry type: POLYGON
#> Dimension: XY
#> Bounding box: xmin: 265638 ymin: 299436.3 xmax: 278974.9 ymax: 326430.3
#> Projected CRS: NAD_1983_HARN_StatePlane_Missouri_East_FIPS_2401
#> First 10 features:
#> OBJECTID WARD AREA TOTAL_E geometry
#> 1 1 1 46138761 7959.092 POLYGON ((272762.8 317484.8...
#> 2 2 2 267817711 12110.535 POLYGON ((275044.1 320169.6...
#> 3 3 3 66291644 7356.539 POLYGON ((275469.4 315093.9...
#> 4 4 4 53210707 8457.699 POLYGON ((272072.6 315153.2...
#> 5 5 5 60462396 8807.580 POLYGON ((277328.1 312562.2...
#> 6 6 6 64337271 14052.998 POLYGON ((274902.5 310971.6...
#> 7 7 7 101268146 15841.502 POLYGON ((278014.2 310777.7...
#> 8 8 8 45966410 12188.988 POLYGON ((272184.4 308794.1...
#> 9 9 9 73993891 14217.903 POLYGON ((274931.9 307729.1...
#> 10 10 10 62915358 11239.120 POLYGON ((269582.8 308190.9...
aw_interpolate(ar_stl_wards, tid = WARD, source = ar_stl_asthma, sid = GEOID, weight = "sum",
output = "tibble", intensive = "ASTHMA")
#> # A tibble: 28 × 4
#> OBJECTID WARD AREA ASTHMA
#> <dbl> <int> <dbl> <dbl>
#> 1 1 1 46138761. 13.4
#> 2 2 2 267817711. 13.2
#> 3 3 3 66291644. 14.1
#> 4 4 4 53210707. 13.6
#> 5 5 5 60462396. 13.8
#> 6 6 6 64337271. 11.7
#> 7 7 7 101268146. 9.72
#> 8 8 8 45966410. 9.82
#> 9 9 9 73993891. 11.8
#> 10 10 10 62915358. 9.44
#> # … with 18 more rows