geometr
Overview
The geometr package provides tools that generate and process easily
accessible and tidy geometric shapes (of class geom). Moreover, it
aims to improve interoperability of spatial and other geometric classes.
Spatial classes are typically a collection of geometric shapes (or their
vertices) that are accompanied by various metadata (such as attributes
and a coordinate reference system). Most spatial classes are thus
conceptually quite similar, yet a common standard lacks for accessing
features, vertices or the metadata. Geometr fills this gap by
providing tools
- that produce an identical output for the same metadata of different classes (via so-called getters) and
- that use an identical input to write to various classes that originally require different input (via so-called setters).
Installation
- Install the latest development version from github:
devtools::install_github("EhrmannS/geometr")The vignette gives an in depth introduction, explains the take on interoperability and discusses the spatial class
geomthat comes withgeometr.Have fun being a geometer!
Examples
Create a geom
library(geometr)
# ... from other classes
library(sf)
#> Linking to GEOS 3.7.0, GDAL 2.4.0, PROJ 5.2.0
nc_sf <- st_read(system.file("shape/nc.shp", package="sf"), quiet = TRUE)
nc_geom <- gc_geom(input = nc_sf)
# ... or by hand.
library(tibble)
coords <- tibble(x = c(40, 70, 70, 50),
y = c(40, 40, 60, 70))
window <- tibble(x = c(0, 80),
y = c(0, 80))
aGeom <- gs_polygon(anchor = coords, window = window)
# The "tiny map" shows where the vertices are concentrated.
nc_geom
#> geom polygon
#> 108 features | 2529 points
#> crs +proj=longlat +datum=NAD27 +no_defs
#> attributes (features) AREA, PERIMETER, CNTY_, CNTY_ID, NAME, FIPS, FIPSNO, CRESS_ID, BIR74, ...
#> tiny map 36.59
#> ◌ ○ ◌ ○
#> ○ ○ ○ ○
#> ◌ ◌ ○ ◌
#> -84.32 ◌ ◌ ◌ ◌ -75.46
#> 33.88Metadata of different classes can be extracted in interoperable quality (i.e. the same metadata in the same arrangement).
getTable(x = nc_sf)
#> Registered S3 method overwritten by 'cli':
#> method from
#> print.boxx spatstat
#> # A tibble: 108 x 16
#> fid gid AREA PERIMETER CNTY_ CNTY_ID NAME FIPS FIPSNO CRESS_ID
#> <int> <int> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <int>
#> 1 1 1 0.114 1.44 1825 1825 Ashe 37009 37009 5
#> 2 2 2 0.061 1.23 1827 1827 Alle… 37005 37005 3
#> 3 3 3 0.143 1.63 1828 1828 Surry 37171 37171 86
#> 4 4 4 0.07 2.97 1831 1831 Curr… 37053 37053 27
#> 5 5 4 0.07 2.97 1831 1831 Curr… 37053 37053 27
#> 6 6 4 0.07 2.97 1831 1831 Curr… 37053 37053 27
#> 7 7 5 0.153 2.21 1832 1832 Nort… 37131 37131 66
#> 8 8 6 0.097 1.67 1833 1833 Hert… 37091 37091 46
#> 9 9 7 0.062 1.55 1834 1834 Camd… 37029 37029 15
#> 10 10 8 0.091 1.28 1835 1835 Gates 37073 37073 37
#> # … with 98 more rows, and 6 more variables: BIR74 <dbl>, SID74 <dbl>,
#> # NWBIR74 <dbl>, BIR79 <dbl>, SID79 <dbl>, NWBIR79 <dbl>
getTable(x = nc_geom, slot = "feature")
#> # A tibble: 108 x 16
#> fid gid AREA PERIMETER CNTY_ CNTY_ID NAME FIPS FIPSNO CRESS_ID
#> <int> <int> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <int>
#> 1 1 1 0.114 1.44 1825 1825 Ashe 37009 37009 5
#> 2 2 2 0.061 1.23 1827 1827 Alle… 37005 37005 3
#> 3 3 3 0.143 1.63 1828 1828 Surry 37171 37171 86
#> 4 4 4 0.07 2.97 1831 1831 Curr… 37053 37053 27
#> 5 5 4 0.07 2.97 1831 1831 Curr… 37053 37053 27
#> 6 6 4 0.07 2.97 1831 1831 Curr… 37053 37053 27
#> 7 7 5 0.153 2.21 1832 1832 Nort… 37131 37131 66
#> 8 8 6 0.097 1.67 1833 1833 Hert… 37091 37091 46
#> 9 9 7 0.062 1.55 1834 1834 Camd… 37029 37029 15
#> 10 10 8 0.091 1.28 1835 1835 Gates 37073 37073 37
#> # … with 98 more rows, and 6 more variables: BIR74 <dbl>, SID74 <dbl>,
#> # NWBIR74 <dbl>, BIR79 <dbl>, SID79 <dbl>, NWBIR79 <dbl>A geom has three attribute tables, one for vertices, one for features
and one for groups of features, all of which can be provided with
ancillary information (details on data structure of a
geom.
getTable(x = nc_geom, slot = "point")
#> # A tibble: 2,529 x 3
#> x y fid
#> <dbl> <dbl> <int>
#> 1 -81.5 36.2 1
#> 2 -81.5 36.3 1
#> 3 -81.6 36.3 1
#> 4 -81.6 36.3 1
#> 5 -81.7 36.4 1
#> 6 -81.7 36.5 1
#> 7 -81.7 36.5 1
#> 8 -81.7 36.6 1
#> 9 -81.3 36.6 1
#> 10 -81.3 36.5 1
#> # … with 2,519 more rowsGroups of features are called multi* features in other packages. By
lumping several closed geometric shapes into one multi* feature, the
separate geometric shapes can’t be attributed with ancillary information
any more. In a geom, multi* features are separated into distinct
(simpler) features, while the attributes of multi* features can be
captured by the group attribute table.
nc_geom2 <- gc_geom(input = nc_sf, group = TRUE)
currituck <- getSubset(x = nc_geom2, gid == 4)
getTable(x = currituck, slot = "feature")
#> # A tibble: 3 x 2
#> fid gid
#> <int> <int>
#> 1 4 4
#> 2 5 4
#> 3 6 4
getTable(x = currituck, slot = "group")
#> # A tibble: 1 x 15
#> gid AREA PERIMETER CNTY_ CNTY_ID NAME FIPS FIPSNO CRESS_ID BIR74
#> <int> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <int> <dbl>
#> 1 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> # … with 5 more variables: SID74 <dbl>, NWBIR74 <dbl>, BIR79 <dbl>,
#> # SID79 <dbl>, NWBIR79 <dbl>Visualise a geom and use quick options to scale attributes to plot
properties.
visualise(`North Carolina` = nc_geom)visualise(`NC - NWBIR74` = nc_geom, fillcol = NWBIR74)A geom has the slot @window, which contains a reference window. This
reference window can be used or modified in many functions of geometr
visualise(`Currituck` = currituck, window = getExtent(currituck))Finally, cast a geom to another type simply by providing it in
anchor of the respective type
library(magrittr)
boundPoints <- gs_point(anchor = currituck) %>%
setWindow(to = getExtent(.))
visualise(`Currituck - boundary vertices`= boundPoints)