Construct an sftime object from all its components

Construct an sftime object from all its components

Usage

st_sftime(
  ...,
  agr = sf::NA_agr_,
  row.names,
  stringsAsFactors = TRUE,
  crs,
  precision,
  sf_column_name = NULL,
  time_column_name = NULL,
  check_ring_dir = FALSE,
  sfc_last = TRUE,
  time_column_last = TRUE
)

# S3 method for sftime
[(x, i, j, ..., drop = FALSE, op = sf::st_intersects)

# S3 method for sftime
[[(x, i) <- value

# S3 method for sftime
$(x, i) <- value

Arguments

...: Column elements to be binded into an sftime object or a single list or data.frame with such columns. At least one of these columns shall be a geometry list-column of class sfc and one shall be a time column (to be specified with time_column_name).
agr: A character vector; see details below.
row.names: row.names for the created sf object.
stringsAsFactors: A logical value; see st_read.
crs: Coordinate reference system, something suitable as input to st_crs.
precision: A numeric value; see st_as_binary.
sf_column_name: A character value; name of the active list-column with simple feature geometries; in case there is more than one and sf_column_name is NULL, the first one is taken.
time_column_name: A character value; name of the active time column. In case time_column_name is NULL, the first POSIXct column is taken. If there is no POSIXct column, the first Date column is taken.
check_ring_dir: A logical value; see st_read.
sfc_last: A logical value; if TRUE, sfc columns are always put last, otherwise column order is left unmodified.
time_column_last: A logical value; if TRUE, the active time column is always put last, otherwise column order is left unmodified. If both sfc_last and time_column_last are TRUE, the active time column is put last.
x: An object of class sf.
i: Record selection, see [.data.frame
j: Variable selection, see [.data.frame
drop: A logical value, default FALSE; if TRUE drop the geometry column and return a data.frame, else make the geometry sticky and return an sf object.
op: A function; geometrical binary predicate function to apply when i is a simple feature object.
value: An object to insert into x or with which to rename columns of x.

Value

st_sftime: An object of class sftime.

Returned objects for subsetting functions: [.sf will return a data.frame or vector if the geometry column (of class sfc) is dropped (drop=TRUE), an sfc object if only the geometry column is selected, and otherwise return an sftime object.

Details

See also [.data.frame; for [.sftime ... arguments are passed to op.

Examples

## construction with an sfc object
library(sf)
g <- st_sfc(st_point(1:2))
tc <- Sys.time()
st_sftime(a = 3, g, time = tc)
#> Spatiotemporal feature collection with 1 feature and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 2 xmax: 1 ymax: 2
#> CRS:           NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Representing 2023-09-01 10:23:34.123624.
#>   a           g                time
#> 1 3 POINT (1 2) 2023-09-01 10:23:34

## construction with an sf object
if (FALSE) {
st_sftime(st_sf(a = 3, g), time = tc) 
# error, because if ... contains a data.frame-like object, no other objects 
# may be passed through ... . Instead, add the time column before.
}

st_sftime(st_sf(a = 3, g, time = tc))
#> Spatiotemporal feature collection with 1 feature and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 2 xmax: 1 ymax: 2
#> CRS:           NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Representing 2023-09-01 10:23:34.123624.
#>   a           g                time
#> 1 3 POINT (1 2) 2023-09-01 10:23:34

## Subsetting
g <- st_sfc(st_point(c(1, 2)), st_point(c(1, 3)), st_point(c(2, 3)), 
     st_point(c(2, 1)), st_point(c(3, 1)))
tc <- Sys.time() + 1:5
x <- st_sftime(a = 1:5, g, time = tc)

# rows
x[1, ]
#> Spatiotemporal feature collection with 1 feature and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 2 xmax: 1 ymax: 2
#> CRS:           NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Representing 2023-09-01 10:23:35.136596.
#>   a           g                time
#> 1 1 POINT (1 2) 2023-09-01 10:23:35
class(x[1, ])
#> [1] "sftime"     "sf"         "data.frame"

x[x$a < 3, ]
#> Spatiotemporal feature collection with 2 features and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 2 xmax: 1 ymax: 3
#> CRS:           NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Ranging from 2023-09-01 10:23:35.136596 to 2023-09-01 10:23:36.136596.
#>   a           g                time
#> 1 1 POINT (1 2) 2023-09-01 10:23:35
#> 2 2 POINT (1 3) 2023-09-01 10:23:36
class(x[x$a < 3, ])
#> [1] "sftime"     "sf"         "data.frame"

# columns
x[, 1]
#> Simple feature collection with 5 features and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 1 xmax: 3 ymax: 3
#> CRS:           NA
#>   a           g
#> 1 1 POINT (1 2)
#> 2 2 POINT (1 3)
#> 3 3 POINT (2 3)
#> 4 4 POINT (2 1)
#> 5 5 POINT (3 1)
class(x[, 1]) # drops time column as for ordinary data.frame subsetting, 
#> [1] "sf"         "data.frame"
# keeps geometry column of sf object

x[, 3]
#> Spatiotemporal feature collection with 5 features and 0 fields
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 1 xmax: 3 ymax: 3
#> CRS:           NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Ranging from 2023-09-01 10:23:35.136596 to 2023-09-01 10:23:39.136596.
#>                  time           g
#> 1 2023-09-01 10:23:35 POINT (1 2)
#> 2 2023-09-01 10:23:36 POINT (1 3)
#> 3 2023-09-01 10:23:37 POINT (2 3)
#> 4 2023-09-01 10:23:38 POINT (2 1)
#> 5 2023-09-01 10:23:39 POINT (3 1)
class(x[, 3]) # keeps time column because it is explicitly selected,
#> [1] "sftime"     "sf"         "data.frame"
# keeps geometry column of sf object, returns an sftime object

x[, 3, drop = TRUE] 
#> [1] "2023-09-01 10:23:35 UTC" "2023-09-01 10:23:36 UTC"
#> [3] "2023-09-01 10:23:37 UTC" "2023-09-01 10:23:38 UTC"
#> [5] "2023-09-01 10:23:39 UTC"
class(x[, 3, drop = TRUE]) # if the geometry column is dropped, not only the
#> [1] "POSIXct" "POSIXt" 
# sf class is dropped, but also the sftime class

x["a"]
#> Simple feature collection with 5 features and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 1 xmax: 3 ymax: 3
#> CRS:           NA
#>   a           g
#> 1 1 POINT (1 2)
#> 2 2 POINT (1 3)
#> 3 3 POINT (2 3)
#> 4 4 POINT (2 1)
#> 5 5 POINT (3 1)
class(x["a"]) # Time columns are not sticky: If a column is selected by a 
#> [1] "sf"         "data.frame"
# character vector and this does not contain the active time column, the time 
# column is dropped. 

x[c("a", "time")]
#> Spatiotemporal feature collection with 5 features and 1 field
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 1 xmax: 3 ymax: 3
#> CRS:           NA
#> Time column with classes: 'POSIXct', 'POSIXt'.
#> Ranging from 2023-09-01 10:23:35.136596 to 2023-09-01 10:23:39.136596.
#>   a                time           g
#> 1 1 2023-09-01 10:23:35 POINT (1 2)
#> 2 2 2023-09-01 10:23:36 POINT (1 3)
#> 3 3 2023-09-01 10:23:37 POINT (2 3)
#> 4 4 2023-09-01 10:23:38 POINT (2 1)
#> 5 5 2023-09-01 10:23:39 POINT (3 1)
class(x[c("a", "time")]) # keeps the time column
#> [1] "sftime"     "sf"         "data.frame"

# with sf or sftime object 
pol = st_sfc(st_polygon(list(cbind(c(0,2,2,0,0),c(0,0,2,2,0)))))
h = st_sf(r = 5, pol)

x[h, ] 
#> Simple feature collection with 2 features and 2 fields
#> Geometry type: POINT
#> Dimension:     XY
#> Bounding box:  xmin: 1 ymin: 1 xmax: 2 ymax: 2
#> CRS:           NA
#>   a           g                time
#> 1 1 POINT (1 2) 2023-09-01 10:23:35
#> 4 4 POINT (2 1) 2023-09-01 10:23:38
class(x[h, ]) # returns sftime object
#> [1] "sf"         "data.frame"

h[x, ] 
#> Simple feature collection with 1 feature and 1 field
#> Geometry type: POLYGON
#> Dimension:     XY
#> Bounding box:  xmin: 0 ymin: 0 xmax: 2 ymax: 2
#> CRS:           NA
#>   r                            pol
#> 1 5 POLYGON ((0 0, 2 0, 2 2, 0 ...
class(h[x, ]) # returns sf object
#> [1] "sf"         "data.frame"

## Assigning values to columns

# assigning new values to a non-time column
x[["a"]] <- 5:1
class(x)
#> [1] "sftime"     "sf"         "data.frame"

# assigning allowed new values to the time column
x[["time"]] <- Sys.time() + 1:5
class(x)
#> [1] "sftime"     "sf"         "data.frame"

# assigning new values to the time column which invalidate the time column
x[["time"]] <- list(letters[1:2])
class(x)
#> [1] "sftime"     "sf"         "data.frame"

# assigning new values with `$`
x$time <- Sys.time() + 1:5
class(x)
#> [1] "sftime"     "sf"         "data.frame"