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
- use an identical input to write to various classes that originally require different input (via so-called setters).
Installation
- Install the official version from CRAN:
install.packages("geometr")or 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 3.5.1, GDAL 2.2.2, PROJ 4.9.2
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
#> 100 groups | 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 different objects/classes have the same name and the same arrangement).
getFeatures(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 BIR74
#> <int> <int> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <int> <dbl>
#> 1 1 1 0.114 1.44 1825 1825 Ashe 37009 37009 5 1091
#> 2 2 2 0.061 1.23 1827 1827 Alle… 37005 37005 3 487
#> 3 3 3 0.143 1.63 1828 1828 Surry 37171 37171 86 3188
#> 4 4 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> 5 5 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> 6 6 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> 7 7 5 0.153 2.21 1832 1832 Nort… 37131 37131 66 1421
#> 8 8 6 0.097 1.67 1833 1833 Hert… 37091 37091 46 1452
#> 9 9 7 0.062 1.55 1834 1834 Camd… 37029 37029 15 286
#> 10 10 8 0.091 1.28 1835 1835 Gates 37073 37073 37 420
#> # … with 98 more rows, and 5 more variables: SID74 <dbl>, NWBIR74 <dbl>,
#> # BIR79 <dbl>, SID79 <dbl>, NWBIR79 <dbl>
getFeatures(x = nc_geom)
#> # A tibble: 108 x 16
#> fid gid AREA PERIMETER CNTY_ CNTY_ID NAME FIPS FIPSNO CRESS_ID BIR74
#> <int> <int> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <int> <dbl>
#> 1 1 1 0.114 1.44 1825 1825 Ashe 37009 37009 5 1091
#> 2 2 2 0.061 1.23 1827 1827 Alle… 37005 37005 3 487
#> 3 3 3 0.143 1.63 1828 1828 Surry 37171 37171 86 3188
#> 4 4 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> 5 5 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> 6 6 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508
#> 7 7 5 0.153 2.21 1832 1832 Nort… 37131 37131 66 1421
#> 8 8 6 0.097 1.67 1833 1833 Hert… 37091 37091 46 1452
#> 9 9 7 0.062 1.55 1834 1834 Camd… 37029 37029 15 286
#> 10 10 8 0.091 1.28 1835 1835 Gates 37073 37073 37 420
#> # … with 98 more rows, and 5 more variables: SID74 <dbl>, NWBIR74 <dbl>,
#> # BIR79 <dbl>, SID79 <dbl>, NWBIR79 <dbl>geometr only knows the feature types point, line, polygon and
grid (a systematic lattice of points). In contrast to the simple
features standard, there are no MULTI* features. The way simple
features have been implemented in R means that the same information can
be stored in several different ways, which are only interoperable after
a range of tests and corrections. For example, a group of polygons can
make up a MULTIPOLYGON with attributes that are valid for the overall
group only. Likewise, the polygons could be stored at the level of
individual "closed paths" as POLYGON, with specific attributes per
polygon. Both sets of attributes can only exists either as duplicates
for all group specific attributes in a POLYGON, or even more
complicated nested attribute tables at the MULTIPOLYGON level.
The backbone of a geom are three attribute tables, one for points,
features and groups of features, the latter two of which can be provided
with ancillary information. Each feature is stored as a single unit, all
of which are related to other features by a group ID, which relates the
features to attributes for an overall group. Eventually this results in
a tidier data-structure with easier access than Spatial* of sf
objects and with higher
versatility.
# when using the group = TRUE argument, the attributes of MULTI*-feature are
# stored in the group attribute table of a geom
nc_geom <- gc_geom(input = nc_sf, group = TRUE)
currituck <- getFeatures(x = nc_geom, gid == 4)
getFeatures(x = currituck)
#> # A tibble: 3 x 2
#> fid gid
#> <int> <int>
#> 1 4 4
#> 2 5 4
#> 3 6 4
getGroups(x = currituck)
#> # A tibble: 1 x 15
#> gid AREA PERIMETER CNTY_ CNTY_ID NAME FIPS FIPSNO CRESS_ID BIR74 SID74
#> <int> <dbl> <dbl> <dbl> <dbl> <fct> <fct> <dbl> <int> <dbl> <dbl>
#> 1 4 0.07 2.97 1831 1831 Curr… 37053 37053 27 508 1
#> # … with 4 more variables: NWBIR74 <dbl>, BIR79 <dbl>, SID79 <dbl>,
#> # NWBIR79 <dbl>
# and new attributes can be set easily,
newTable <- data.frame(fid = c(1:108),
attrib = rnorm(108))
(nc_geom <- setFeatures(x = nc_geom, table = newTable))
#> geom polygon
#> 100 groups | 108 features | 2529 points
#> crs +proj=longlat +datum=NAD27 +no_defs
#> attributes (features) attrib
#> (groups) AREA, PERIMETER, CNTY_, CNTY_ID, NAME, FIPS, FIPSNO, CRESS_ID, BIR74, ...
#> tiny map 36.59
#> ◌ ○ ◌ ○
#> ○ ○ ○ ○
#> ◌ ◌ ○ ◌
#> -84.32 ◌ ◌ ◌ ◌ -75.46
#> 33.88geometr comes with the visualise function, which makes nice-looking
diagnostic spatial plots, that show explicit values whenever possible.
For example, it does not create artificial bins for the values scale,
but shows the explicit range of values. Moreover, you can easily set
plot titles without much effort.
visualise(`North Carolina` = nc_geom)By default, visualise uses the feature ID as fillcolour. You can use
quick options to modify which aspect given object should be shown in the
plot, for example to scale the fillcolour to the attribute NWBIR74.
myAttr <- "NWBIR74"
visualise(!!paste0("NC - ", myAttr) := nc_geom, fillcol = !!myAttr)Each 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, linecol = fid)