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Convert SpatialPointsDataframe to SpatialPolygons in R

I have a SpatialPointsDataFrame in R that looks like this:

              coordinates id order  hole piece group box_id
    326  (-94.4, 27.6586) 47     1 FALSE     1  47.1      1
    327 (-93.64, 27.6232) 47     2 FALSE     1  47.1      1
    328 (-92.04, 27.7649) 47     3 FALSE     1  47.1      1
    329 (-90.36, 27.0903) 47     4 FALSE     1  47.1      1
    330 (-91.12, 25.6929) 47     5 FALSE     1  47.1      1
    331 (-92.92, 25.6569) 47     6 FALSE     1  47.1      1
    332 (-93.44, 26.0169) 47     7 FALSE     1  47.1      1
    333  (-94.4, 25.9809) 47     8 FALSE     1  47.1      1
    334  (-94.4, 27.6586) 47     9 FALSE     1  47.1      1
    335 (-92.04, 27.7649) 48     1 FALSE     1  48.1      2
    336 (-93.64, 27.6232) 48     2 FALSE     1  48.1      2
    337  (-94.4, 27.6586) 48     3 FALSE     1  48.1      2
    338  (-94.4, 27.8356) 48     4 FALSE     1  48.1      2
    339 (-93.64, 27.7649) 48     5 FALSE     1  48.1      2
    340 (-90.28, 28.1182) 48     6 FALSE     1  48.1      2
    341 (-90.56, 27.9417) 48     7 FALSE     1  48.1      2
    342 (-92.04, 27.7649) 48     8 FALSE     1  48.1      2
    100  (-94.4, 27.8356) 20     1 FALSE     1  20.1      3
    101  (-94.4, 28.0829) 20     2 FALSE     1  20.1      3
    102 (-90.28, 28.1182) 20     3 FALSE     1  20.1      3
    103 (-93.64, 27.7649) 20     4 FALSE     1  20.1      3
    104  (-94.4, 27.8356) 20     5 FALSE     1  20.1      3

(the names / line numbers are out of order, as I am sorted by the box_id column)

These points are nodes of the polygons (denoted by box_id). I want to write this as a polygon shape file for reading to GIS programs, but I find it difficult to convert it to a SpatialPolygonDataFrame (to use writeOGR then) or write it directly to the shp file. Any help would be appreciated. I am new to GIS with R, so I apologize if I am missing something obvious.

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, , @JoshO'Brien's. ( ) SpatialPolygonsDataFrame (, ). ESRI.

, , SpatialPointsDataFrame , . id Polygon id, group . 3 , 1 , - 3 . data ( ), box_id.

# this code just creates a sample SpatialPointsDataFrame 
x <- c(-10,-10,10,10,-10)
y <- c(-10,10,10,-10,-10)
df.1 <- data.frame(x,y,id=47, order=1:5,hole=F,piece=1,group=47.1,box_id=1)
coordinates(df.1)=c("x","y")
x <- c(+15+3*cos(2*pi/5*(0:5)))
y <- c(-15+3*sin(2*pi/5*(0:5)))
df.2 <- data.frame(x,y,id=48, order=1:6,hole=F,piece=1,group=48.1,box_id=2)
coordinates(df.2)=c("x","y")
x <- c(-15+2*cos(2*pi/8*(0:8)))
y <- c(+15+2*sin(2*pi/8*(0:8)))
df.3.1 <- data.frame(x,y,id=20, order=1:9,hole=F,piece=1,group=20.1,box_id=3)
coordinates(df.3.1)=c("x","y")
x <- c(0+2*cos(2*pi/8*(0:8)))
y <- c(+15+2*sin(2*pi/8*(0:8)))
df.3.2 <- data.frame(x,y,id=20, order=1:9,hole=F,piece=1,group=20.2,box_id=3)
coordinates(df.3.2)=c("x","y")
x <- c(+15+2*cos(2*pi/8*(0:8)))
y <- c(+15+2*sin(2*pi/8*(0:8)))
df.3.3 <- data.frame(x,y,id=20, order=1:9,hole=F,piece=1,group=20.3,box_id=3)
coordinates(df.3.3)=c("x","y")
df <- rbind(df.1,df.2,df.3.1,df.3.2,df.3.3)
df
#              coordinates id order  hole piece group box_id
# 1             (-10, -10) 47     1 FALSE     1  47.1      1
# 2              (-10, 10) 47     2 FALSE     1  47.1      1
# 3               (10, 10) 47     3 FALSE     1  47.1      1
# 4              (10, -10) 47     4 FALSE     1  47.1      1
# 5             (-10, -10) 47     5 FALSE     1  47.1      1
# 6              (18, -15) 48     1 FALSE     1  48.1      2
# 7  (15.92705, -12.14683) 48     2 FALSE     1  48.1      2
# 8  (12.57295, -13.23664) 48     3 FALSE     1  48.1      2
# ...
data <- data.frame(box_id=unique(df$box_id),row.names=unique(df$id))

points2polygons(...). SpatialPointsDataFrame , .

points2polygons <- function(df,data) {
  get.grpPoly <- function(group,ID,df) {
         Polygon(coordinates(df[df$id==ID & df$group==group,]))
         }
  get.spPoly  <- function(ID,df) {
         Polygons(lapply(unique(df[df$id==ID,]$group),get.grpPoly,ID,df),ID)
         }
  spPolygons  <- SpatialPolygons(lapply(unique(df$id),get.spPoly,df))
  SpatialPolygonsDataFrame(spPolygons,match.ID=T,data=data)
}
spDF <- points2polygons(df,data)
plot(spDF,col=spDF$box_id+1)

library(rgdal)
writeOGR(spDF,dsn=".",layer="myShapefile", driver="ESRI Shapefile")

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