Aquí se mostrará como agregar atributos a un objetos sf

Lo primero es cargar la librería sf:

library(sf)

ahora leemos un shapefile de los municipios de mi departamento:

(Mun_valle <- read_sf("val_mun.shp"))
Simple feature collection with 42 features and 6 fields
geometry type:  MULTIPOLYGON
dimension:      XY
bbox:           xmin: -81.61708 ymin: 2.931806 xmax: -75.7098 ymax: 4.975899
epsg (SRID):    4326
proj4string:    +proj=longlat +datum=WGS84 +no_defs

Ahora identificamos la clase de la variable que tenemos, para eso utilizo la función class():

class(Mun_valle)
[1] "sf"         "tbl_df"     "tbl"        "data.frame"

uso la función attribute() para conocer los atributos de mi shapefile:

attributes(Mun_valle)
$names
[1] "ISO"       "NAME_0"    "NAME_1"    "NAME_2"    "TYPE_2"    "ENGTYPE_2"
[7] "geometry" 

$row.names
 [1]  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
[25] 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42

$class
[1] "sf"         "tbl_df"     "tbl"        "data.frame"

$sf_column
[1] "geometry"

$agr
      ISO    NAME_0    NAME_1    NAME_2    TYPE_2 ENGTYPE_2 
     <NA>      <NA>      <NA>      <NA>      <NA>      <NA> 
Levels: constant aggregate identity
st_crs(Mun_valle)

Uso la función st_bbox() para recuperar la caja envolvente de mi departamento:

st_bbox(Mun_valle)
      xmin       ymin       xmax       ymax 
-81.617081   2.931806 -75.709801   4.975899

Ahora descargo los paquetes units y lwgeom:

install.packages("units")
Error in install.packages : Updating loaded packages
install.packages("lwgeom")
WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:

https://cran.rstudio.com/bin/windows/Rtools/
Installing package into 㤼㸱C:/Users/CABRERA/Documents/R/win-library/3.6㤼㸲
(as 㤼㸱lib㤼㸲 is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/lwgeom_0.1-7.zip'
Content type 'application/zip' length 5200836 bytes (5.0 MB)
downloaded 5.0 MB
package ‘lwgeom’ successfully unpacked and MD5 sums checked

The downloaded binary packages are in
    C:\Users\CABRERA\AppData\Local\Temp\RtmpGicT86\downloaded_packages
install.packages("units")
WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:

https://cran.rstudio.com/bin/windows/Rtools/
Installing package into 㤼㸱C:/Users/CABRERA/Documents/R/win-library/3.6㤼㸲
(as 㤼㸱lib㤼㸲 is unspecified)
trying URL 'https://cran.rstudio.com/bin/windows/contrib/3.6/units_0.6-5.zip'
Content type 'application/zip' length 1757610 bytes (1.7 MB)
downloaded 1.7 MB
package ‘units’ successfully unpacked and MD5 sums checked
Warning in install.packages :
  cannot remove prior installation of package ‘units’
Warning in install.packages :
  problem copying C:\Users\CABRERA\Documents\R\win-library\3.6\00LOCK\units\libs\x64\units.dll to C:\Users\CABRERA\Documents\R\win-library\3.6\units\libs\x64\units.dll: Permission denied
Warning in install.packages :
  restored ‘units’

The downloaded binary packages are in
    C:\Users\CABRERA\AppData\Local\Temp\RtmpGicT86\downloaded_packages
library(lwgeom)
Linking to liblwgeom 2.5.0dev r16016, GEOS 3.6.1, PROJ 4.9.3
library(units)
udunits system database from C:/Users/CABRERA/Documents/R/win-library/3.6/units/share/udunits

Calculo de área

Utilizo la función st_area() para calcular el área de cada uno de los municipios de mi departamento, eso lo guardo en una nueva variable que llamaré Mun_valle$area que me diferencia el area de otros atributos:

(Mun_valle$area <- st_area(Mun_valle))
Units: [m^2]
 [1]   90473278  217037317  317633248  193841997  695820520 6789961578
 [7]  371490773  131566706  829249011  260718595  354942250  797823378
[13]  270854215  145154379  506817569  327785029  434966936  232890424
[19]  188217360  975698436  683322745  205687416  123932908  309700291
[25]  149545306 1036861962  427677544  136320205  238461088  274895749
[31]  300769314  503339237  920251798  192057393  241248270  608834117
[37]   65844783  448327809  170367579  318317944  158853900  354388187

Uso la función set_units()

#cambio de unidades de area
set_units(Mun_valle$area, km^2)
Units: [km^2]
 [1]   90.47328  217.03732  317.63325  193.84200  695.82052 6789.96158
 [7]  371.49077  131.56671  829.24901  260.71860  354.94225  797.82338
[13]  270.85422  145.15438  506.81757  327.78503  434.96694  232.89042
[19]  188.21736  975.69844  683.32275  205.68742  123.93291  309.70029
[25]  149.54531 1036.86196  427.67754  136.32020  238.46109  274.89575
[31]  300.76931  503.33924  920.25180  192.05739  241.24827  608.83412
[37]   65.84478  448.32781  170.36758  318.31794  158.85390  354.38819

library(readxl)
(my_data <- read_excel("CensoAgropecuario.xls"))

joining censo data to simple feature project

Para esta parte hay que asegurarnos de que la libreria tidyverse este ejecutado:

(valle_data <- my_data %>% filter(Departamento == "Valle del Cauca"))
(valle_ndata <- rename(valle_data, NAME_2=Municipios))

llego el tiempo de hacer una union left_join:

(valle_censo <- left_join(Mun_valle, valle_ndata))
Joining, by = "NAME_2"
Simple feature collection with 42 features and 14 fields
geometry type:  MULTIPOLYGON
dimension:      XY
bbox:           xmin: -81.61708 ymin: 2.931806 xmax: -75.7098 ymax: 4.975899
epsg (SRID):    4326
proj4string:    +proj=longlat +datum=WGS84 +no_defs

Visualización

Ahora utilizo la librería mapview para hacer el mapa de mi municipio con los nuevos atributos que le añadi:

install.packages("mapview")
Error in install.packages : Updating loaded packages
suppressPackageStartupMessages(library(mapview))
valle_censo %>% mapview(zcol = "NAME_2", legend = TRUE, col.regions = sf.colors)

install.packages("mapview")
WARNING: Rtools is required to build R packages but is not currently installed. Please download and install the appropriate version of Rtools before proceeding:

https://cran.rstudio.com/bin/windows/Rtools/
Installing package into 㤼㸱C:/Users/CABRERA/Documents/R/win-library/3.6㤼㸲
(as 㤼㸱lib㤼㸲 is unspecified)
Warning in install.packages :
  package ‘mapview’ is in use and will not be installed

Ordenar los datos

ahora vamos a ordenar las municipalidades basados en las hectareas de bosque, para eso uso la función ****

(Valle_Balto <- valle_censo %>% arrange(desc(Bosques_Ha))) 
Simple feature collection with 42 features and 14 fields
geometry type:  MULTIPOLYGON
dimension:      XY
bbox:           xmin: -81.61708 ymin: 2.931806 xmax: -75.7098 ymax: 4.975899
epsg (SRID):    4326
proj4string:    +proj=longlat +datum=WGS84 +no_defs
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